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  • Cell & Developmental Biology  (1,654)
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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 151 (1977) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 2
    Electronic Resource
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 151 (1977), S. 81-109 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: (1) In an animal where the corpus allatum complex is inhibited by glucose feeding, the ovariole develops to a certain size without yolk deposition in the oocytes. Histologically this can be registered as: (a) Lipid spheres are found in the young oocytes in the vicinity of the Balbiani body (as in young normal oocytes). However, this lipid decreases in amount and “new” lipid (from the fat body via haemolymph) is not deposited in the later oocytes. (b) No carbohydrate/protein yolk is formed. (c) Glycogen is not synthesized in the oocytes. (d) The follicle cells aggregate glycogen instead of lipid. (e) No qualitative differences have been observed regarding the contributions from the tropharium (the so-called Type 1 vacuole, ribosomes, mitochondria, annulated lamellae: Schreiner, '77).(2) Implantation of a corpus allatum complex results in deposition of lipid, carbohydrate/protein and glycogen yolk. However, the restoration period differs histologically from the normal development as: (a) Glycogen appears in the oocyte earlier than normal, i.e., at Stage 4, while normally at Stage 6′. (b) Glycogen appears in the nutritive tube adjacent to the interfollicular plug cells. (c) Both the inner and outer layer of the ovariole sheath contain glycogen, the outer layer contains lipid spheres as well.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 151 (1977) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 4
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 151 (1977), S. 187-211 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The odontophore and connective tissue-filled portion of the radular sac (called the “collostyle”) of the slug, Limax maximus, were examined by light and electron microscopy. While both of these structures grossly resemble vertebrate cartilage, neither is composed of a type of tissue with the microscopic appearance and histochemical properties of cartilage. The roughly U-shaped odontophore possesses a thin capsule composed of connective tissue. The parenchyma of the odontophore consists of modified muscle cells which are organized into irregular groups by incomplete trabeculae composed of conventional muscle cells. The odontophoral cells are variable in size; they contain glycogen-filled “cores” as well as bundles of peripherally located filaments resembling myofilaments; and they are innervated like muscle cells. The nuclei of the cells are located eccentrically in the glycogen-filled portions of the cells and typically contain prominent nucleoli. The nuclei are surrounded by multiple small Golgi complexes and pleomorphic dense bodies resembling lysosomes. The extracellular matrix of the odontophore is very sparse and contains glycogen and fibrillar material but no histochemically demonstrable acidic mucosubstances. The collostyle consists of a gelatinous type of tissue somewhat like vertebrate mucoid connective tissue. The abundant extracellular matrix contains cross banded filaments, a flocculent material disposed in wavy indefinite strands, and small electron-dense particles. The matrix contains histochemically demonstrable neutral and weakly acidic mucosubstances. The cell population of the collostyle includes solitary muscle cells and fibrocytes containing large quantities of glycogen.
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  • 5
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 151 (1977), S. 213-237 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This ultrastructural study on the localization of Ca+2 in developing skeletal muscle indicates that the formation of calcium-accumulating components begins during embryonic development. Both oxalate and pyroantimonate techniques are used to localize Ca+2 in distinct cellular components of chick pectoral and sartorius muscles. Two major sites for Ca+2 accumulation are present in ultrathin sections of embryonic and post-embryonic muscles: the terminal cisternae of the sarcoplasmic reticulum and specific lines in the I-bands. Calcium oxalate-accumulating vesicles are present in the smallest recognizable myotubes at the twelfth day of incubation, but calcium-accumulating components are not seen at myofibrillar I-band sites until the fourteenth to seventeenth days of incubation. The fact that myofibrils first form and later in development accumulate a Ca+2-binding component suggests that this Ca+2-binding component is not necessary for the formation of myofibrils, but is added to myofibrils before hatching to serve a probable regulatory role in contraction.
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  • 6
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This report is an ultrastructural analysis of the organization of the isolated oral apparatus of Tetrahymena pyriformis, strain WH-6, syngen 1. Attention has been focused on the organization of microtubules and filaments in oral apparatus membranelles. Oral apparatus membranellar basal bodies were characterized with respect to structural differentiations at the distal and proximal ends. The distal region of membranellar basal bodies contains the basal plate, accessory microtubules and filaments. The proximal end contains a dense material from which emanate accessory microtubules and filaments. There are at least two possibly three different arrangements of accessory structures at the proximal end of membranellar basal bodies. All membranellar basal bodies appear to have a dense material at the proximal end from which filaments emanate. Some of these basal bodies have accessory microtubules and filaments emanating from this dense material. A possible third arrangement is represented by basal bodies which have lateral projections, from the proximal end, of accessory microtubules and filaments which constitute cross or peripheral connectives. There are at least three examples of direct associations between oral apparatus microtubules and filaments: (1) filaments which form links between basal body triplet microtubules, (2) filaments which link the material of the basal plate to internal basal body microtubules, (3) filaments which link together microtubule bundles from membranellar connectives. KCI extraction of the isolated oral apparatus resulted in the selective solubilization of oral apparatus basal bodies, remnants of ciliary axonemes and fused basal plates. Based on their response to KCl extraction two distinct sets of morphologically similar microtubules can be identified: (a) microtubules which constitute the internal structure of basal bodies and ciliary axonemes, (b) microtubules which constitute the fiber connectives between basal bodies.
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  • 7
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 151 (1977), S. 353-361 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Ultrastructural analysis of initial development of actinotrichia, the skeleton anlage of the pelvic fin buds, was performed on the rainbow trout, Salmo gairdneri. It shows that the first actinotrichial rudiments appear in the subepidermal space of the pseudoapical cap. No mesenchymal cell bodies or their filopods are present. Hyaloplasmic protrusions of the basal epidermal cells are seen in the subepidermal space, limited by a dermoepidermal boundary reduced to a discontinuous thin adepidermal lamina without a collagenous layer. These morphological data suggest that the epidermal pseudoapical cap probably initiates the development of actinotrichia. Later, mesenchymal cells invade the subepidermal space and are probably involved in the further growth of actinotrichia.
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  • 8
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    Journal of Morphology 151 (1977), S. 397-417 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Synaptic organization of the nucleus rotundus was studied with the electron microscope in three teleost species belonging to the same order. In spite of the different histological organization (non-laminated, incompletely laminated, and laminated), the same kinds of axon terminals (S and F) are observed in all species. A fibrous layer which is clearly formed only in the laminated nucleus is composed of F1 terminals and dendrites from a layer of small cells. The same kind of synapses formed between F1 terminals and dendrites of small cells are also found among glomeruli in the non-laminated and incompletely laminated nuclei. The main constituents of glomeruli are S and F2 terminals and dendrites of large cells in the non-laminated and incompletely laminated nuclei, and are S terminals and star-like structures which correspond to the tips of the dendrites of large cells in the laminated nucleus. The star-like structure contains numerous mitochondria and clusters of small polymorphic vesicles. Some of the vesicles aggregate at thickened cell membranes of the structure as in presynaptic dendrites.
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  • 9
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 152 (1977), S. 247-279 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The intrinsic organization of medial cortex in snakes, primarily of the genera Natrix and Boa, was studied using Golgi and electron microscopic techniques. The area has three distinct layers, each containing a characteristic population of neurons. Stellate cells comprise a relatively small population of neurons with their somata and dendrites restricted to layer 1, the most superficial layer. Their axons course horizontally in layer 1. Candelabra cells form the largest population of neurons in medial cortex. Their somata lie densely packed in layer 2 and are joined by specialized junctions. Ascending dendrites extend from the somata into layer 1. They consist of spine-free proximal segments and spine bearing distal segments. Descending dendrites extend from the somata into the upper half of layer 3. The proximal segments bear few spines but branch into several tapered, distal segments which have a moderate covering of spines. One or two axons originate from the descending dendrites and descend through layer 3. The axons bear collaterals in the deep half of layer 3 and eventually bifurcate in the alveus. The medial branches run into the septum; the lateral branches course through other cortical areas. The axons bear frequent varicosities within medial cortex. Periventricular cells lie in the deep half of layer 3, either singly or in clusters. Their ascending dendrites extend radially into layer 1 where they branch into distal segments which resemble those of the candelabra cells. Their descending dendrites arborize horizontally in the alveus and bear a moderate covering of spines. Ependymal cells line the ventricular surface and send radial processes through the area's depth bearing lamellate processes.
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  • 10
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 152 (1977), S. 329-339 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The sex-linked mutation fs(1)42 was induced by ethyl methane sulfonate. It has no effect on either the external morphology or longevity of adult hemizygotes or homozygotes. Heterozygotes and hemizygotes are fertile, but homozygotes are sterile. Egg chamber development proceeds through stage 8, and thereafter chambers degenerate. Dying follicle cells are seen in chambers at all positions in the ovarioles. Profollicle cells also die within germaria, and clusters of sister cystocytes take longer than normal to receive their coverings of follicle cells. Egg chambers in the vitellarium contain only about 60% the normal number of follicle cells, these generally have greater lateral dimensions, and their nuclei and nucleoli are also larger than normal. The follicular envelope of mutant chambers often contains gaps through which cystocytes send cytoplasmic projections. Abnormalities seen in development of the fs(1)42 oocyte are likely to be due to its envelope of defective follicle cells.
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  • 11
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    Journal of Morphology 152 (1977), S. 363-379 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Reproductive organs of four botryllid ascidians, Botryllus primigenus, Botryllus schlosseri, Botrylloides violaceus and Botrylloides leachi, were studied histologically. In every species, the egg follicle consisting of an egg and its inner and outer follicles, is attached to the follicle stalk, the vesicle being composed of a flat epithelium, which in its turn is connected to the atrial epithelium or to the brood pouch specialized from it. In B. schlosseri, the egg is ovulated into the atrial cavity and remains there held by the brood cup, of which the inner epithelium is derived from the follicle stalk and the outer one from the atrial epithelium. In B. primigenus, the brood pouch develops as a diverticulum of the atrial cavity, around the entrance of which a fold differentiates from the atrial epithelium and closes the pouch during embryogenesis. In both species of Botrylloides, the brood pouch is formed by the outgrowth of the thickened atrial epithelium into the blood space, the entrance of which is closed during embryogenesis. The discarded outer follicle completely disintegrates soon after ovulation in B. schlosseri, but part of it remains throughout embryogenesis in the blood space in B. primigenus or projecting into the interior of the brood pouch in Botrylloides. In B. primigenus, the testis, when it accompanies the egg follicle, is placed at the bottom of the brood pouch and the sperm is shed through the pouch prior to ovulation. In B. schlosseri and the Botrylloides species, the testis is located independently from the egg follicle and the sperm matures after ovulation.
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  • 12
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The cells of the follicular epithelium of the ovarioles of the mosquito, Aedes aegypti (L.), and of the stable fly, Stomoxys calcitrans (L.), have been found to be interconnected by cytoplasmic bridges. Cytoplasmic bridges have been reported between sibling gamete cells of both male and female insects, but these bridges have not been previously reported to exist between somatic cells of insects.
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  • 13
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: An unusual organelle in the oocytes of the marine mud snail Ilyanassa obsoleta is described and called a polymerosome, because of its several components. Polymerosomes appear at the beginning of vitellogenesis and persist, in part, through postvitellogenesis. The persistent part is similar to an organelle that has been described by other workers in the vegetal region and the polar lobe of the Ilyanassa egg.
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  • 14
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 153 (1977) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 15
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    Journal of Morphology 152 (1977), S. 315-327 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: An analysis of mechanical and architectural aspects of three hamstring muscles in the cat, semitendinosus (ST), semimembranosus anterior (SMa), and semimembranosus posterior (SMp), is presented based on whole muscle tetanic tension profiles. Length-active tension curves for each muscle were obtained by electrical stimulation of the whole muscle with a train of stimuli at 100 pulses per second (pps) for 600 milliseconds.Information from motion picture analysis (Goslow et al., '73) and electromyographic (EMG) activity (Engberg and Lundberg, '69) as seen during the step cycle is combined with analysis of joint torques to present a picture of the differential functions of the three muscles. The length-active tension characteristics of ST and SMa are such that they develop high amounts of tension throughout their physiological excursions. Maximal tension is produced over a much more limited range by SMp. A division of labor for the three muscles is proposed: the one-joint SMa is shown to be a primary hip extensor whose action facilitates smooth oscillation of the leg. Torque and electrical activity during the step cycle indicate the two-joint ST is a primary knee flexor. The more limited range of maximum torque and variable EMG pattern of the other two-joint muscle, SMp, relate to the fact that it has primary activity during high speed gaits when it may act to initiate spine flexion and assist in hip extension.Excursion and activity data have led to the conclusion that biarticular muscles (ST and SMp) may benefit from the combined action of two joints to maintain near maximal tension and torque during active phases of the step cycle. Thus, biarticular muscles may have evolved as much for the mechanical and physiological benefits they derive as for two-joint action itself.
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  • 16
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    Journal of Morphology 152 (1977), S. 381-400 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Oogenesis has been investigated utilizing both light and electron microscopical techniques in the squid, Loligo pealei. This complex process has been divided into five stages according to the structure of the follicle. Because of the highly coordinated differentiation of the follicle cells (and follicular syncytium) and the oocyte, their development is described in concert. Specific attention is given to the contribution of the follicular syncytium to vitellogenesis and the formation of the extracellular egg envelope or chorion. Our observations indicate heterosynthetic yolk production and the synthesis of the secondary envelope by the follicular syncytium.
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  • 17
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    Journal of Morphology 153 (1977), S. 39-79 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A recently presented model of tongue projection dynamics is used to generate a series of predictions concerning morphologies to be expected under selection for increased distance of projection, increased speed of projection, and increased directional versatility. A general understanding of biomechanical events and the model are used as points of departure for making specific predictions concerning details of structure in skeletal, muscular and connective tissue components of the tongue and associated structures. Comparative methods are used to examine these predictions in the genera of plethodontid salamanders. These salamanders are known to project their tongues to different degrees, and this knowledge is used to test the hypotheses concerning morphological specialization. Three distinct groups of plethodontid salamanders have evolved specializations for long distance projection, and these genera differ from one another in important ways in respect to specific character complexes. For example, the tropical genera and Hydromantes use CBII as the major force transmission element in the skeleton, while Eurycea and its allies use CBI in this role. Hydromantes differs from both in having a uniquely proportioned and structured hyobranchial skeleton and associated musculature. Less extreme specializations for tongue projection are found in different combinations in three other groups. Finally, two distinct groups of generalized species having only limited tongue projection capabilities are recognized, each having a unique complex of inter-related features. Each of these eight groups is recognized and characterized as a functional mode, and hypotheses concerning the biomechanical meaning of the character complexes of each are formulated.
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  • 18
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The mechanical properties of the whole muscle and fast-twitch muscle units of the cat hindlimb pretibial flexors have been explored and related to normal locomotion. Tibialis anterior (TA) is parallel-fibered and functionally crosses a single joint, the ankle, whereas extensor digitorum longus (EDL) is pinnate and spans the ankle, knee, metatarsophalangeal and interphalangeal joints. The active tetanic tension of TA remains near its peak value over a range of muscle lengths associated with normal ankle movement. In contrast, the length-tension curve of EDL is sharply peaked. However, normal corollary action of the knee, ankle and metatarsophalangeal joints during stepping minimizes EDL's excursion and maintains it at or near a length optimal for peak tension development. EDL is capable of producing synchronous but sterotyped digit and ankle movements while TA provides for independent ankle flexion at all relevant joint angles.The mechanical properties of 84 TA and 98 EDL fast-twitch muscle units were studied by measuring twitch contraction time (≤45 msec), peak tetanic tension, response to repetitive stimulation, and contractile fatigue resistance during electrical stimulation of single alpha axons, functionally isolated from ventral root filaments. These mechanical properties were essentially similar for both muscles with the exception of mean peak tetanic tension which was 30% lower for TA units (14 gm-wt) than for EDL units (20 gm-wt). A high proportion of units in both muscles demonstrated fatigue resistance which is reflective of the repetitive, phasic demand upon these muscles during locomotion.
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  • 19
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    Journal of Morphology 153 (1977), S. 263-297 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A survey is made of some ultrastructural features of the developing cornea of Macaca mulatta. The observations are confined to the anterior central area, starting with the lens vesicle stage and progressing through midgestation, when the morphologic characteristics of the cornea are fully established. Subepithelial filaments and some partially aggregated collagen fibrils are present in the earliest embryo and are of a size and appearance similar to those in the future vitreous cavity. Epithelial secretory activity points to, but does not prove direct contribution to the deposition of the acellular matrix components beneath it. No trace of a structured, orthogonal collagenous stroma can be visualized. The primitive endothelium forms prior to the fibroblast invasion of the distended filamentous matrix. Bowman's layer has undoubted epithelial contributions. Its aggregated collagen fibrils have approximately the same diameter as those of the anterior stroma. Intraepithelial appearance of single nerve fibers and fascicles takes place during the first trimester of gestation, as soon as the two continuous epithelial layers are formed. Terminal areas approach closely to the basal cell's nucleus, without touching it. The plasmalemma of the invaginating nerve fiber is surrounded by that of the epithelial cell in a mesaxon-like manner, with occasional gap junctions uniting adjoining neural and epithelial cell membranes. The fetal neurites contain microtubules, some clear vesicles and dense vacuoles resembling those of mature monamine and non-monamine neurons. Mitochondria are small and compact, their presence indicating a high rate of metabolic activity in the immature terminal area.
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  • 20
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    Journal of Morphology 153 (1977), S. 333-353 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The structural features of sinus hair follicles in Sorex unguiculatus were studied by macroscopic dissection, serial section light microscopy and electron microscopy. The shrew has about 540 sinus hairs regularly arranged on the snout. The maxillary nerves innervating them are extremely thick, while the optic nerves are very thin. Thus the follicle must be one of the most important sense organs in this animal. In the follicle the ring sinus is well-developed and the trabeculae of the cavernous sinus are reduced in number and thickness. The ring bulge is not a unified structure but a pair of bodies which consist of head, stalk and attachment plaque. It is characterized by the presence of numberous thick collagen fibrils (400 nm) and appears to be mechanically rigid. Lanceolate nerve terminals, free endings, Merkel cells with nerve terminals and unmyelinated fibers are observed, but encapsulated endings are lacking in and around the follicles. Straight lanceolate terminals on the posterior side of the follicle are thick and three-sided in cross section, while those on the anterior side are thin and two-sided. Free endings are located on the anterior side of the follicle. These and other findings are discussed on the basis of the assumption that the Sorex sinus hair follicle is more specialized as a vibrating system than in other mammals.
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  • 21
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    Journal of Morphology 153 (1977), S. 371-385 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Neurosecretory cells are arranged in 16 NSC centers in the different regions of the brain of O. tholozani. The component cells belong to 13 different types, of which five types are paraldehyde fuchsin positive and the remaining types are negative. Three of these cell types are here described for the first time. Some of these NSC show an affinity to certain localities inside the brain. Cells comprising a neurohaemal organ were found near the exit of the esophagus.
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  • 22
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    Journal of Morphology 153 (1977), S. 419-425 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Yolk platelets in differentiating embryonic amphibian cells degrade by a membranous “unraveling” or “delamination” process. Acid phosphatase activity was demonstrated at the peripheries of those platelets which were in the process of degrading and thus this lytic enzyme appears to be involved in the breakdown process. We believe that this relationship provides a means by which early cells obtain the nutrients necessary for early differentiation.
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  • 23
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    Journal of Morphology 153 (1977), S. 467-477 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The coelomocytes of Lumbricus terrestris have been classified and described, based on Wright's stained preparations and on living cells. The five major categories consist of basophils, acidophils, neutrophils, granulocytes and chloragogen cells. Both the acidophil and chloragogen cell groups contain two subgroups. Granulocytes also exhibit heterogeneity with respect to staining properties of granules. Some possess acidophilic granules, some basophilic granules, and others contain both types. Granules of acidophils have been observed to be occasionally excreted from the cells. All cell types, with the exception of chloragogen cells, produce pseudopodia and are capable of phagocytosis, a vital component of the earthworm's immune response.
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  • 24
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Newly metamorphosed Kenyan reed frogs, Hyperolius viridiflavus ferniquei, are able to regenerate amputated digits. The terminal digital pad is also completely reformed. Differentiation of the regenerating digital pad was studied by scanning electron microscopy. External differentiation of the digital pad began late in the second postamputational week with the appearance of small patches of specialized epidermal cells on the ventral surface of the regenerating digit. The differentiation of the pad spread out radially until late in the fourth week, when its overall shape approximated that of the normal digital pad. The appearance of patches of digital pad epidermis on the ends of spike regenerates arising from the forearm was also confirmed.
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  • 25
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    Journal of Morphology 153 (1977), S. 427-460 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The objectives of this research were to investigate the morphology of the thoracic skeleton and muscles of the mosquito, Culiseta inornata (Williston). The results are presented in 25 text figures and descriptions of each skeletal part and muscle. Undescribed exoskeletal structures are the postmediotergite, intersegmental cleft on the caudal margin of the metapleuron, and the parascutellar process. This process is considered a homologue of the fourth axillary. The acrotergite 2 and subalifer were identified. The prescutum has been called the paratergite by previous authors. The morphological basis for self amputation of legs is described. Undescribed parts of the endoskeleton are: lateral arm of sternal apophysis 1 and its socket on the mesal surface of coxa 1, furcopleural apodeme on sternal apophysis 1, precoxal and postcoxal apodemes arising from the ventral pleural arm, upper and lower laterotergite apodemes on the postnotum, and the pleural and intersegmental apodemes for attachment of halter muscles. Seventy-two muscles are illustrated with their attachments and the origin, insertion, and action of each is described. Ten of the muscles are newly described for the mosquito. There are no muscles inserted on the subalare, second axillary, or third axillary.
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  • 26
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    Journal of Morphology 154 (1977) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 27
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    Journal of Morphology 154 (1977), S. 1-17 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The results of reversing the polarity of the middle gastric region in Hydra viridis with multiple-gastric region grafts (3grp animals) are contrasted to previously reported results on comparably elongated animals (3g animals) whose middle gastric regions retain their original polarity. The middle gastric regions of 3grp animals are also bisected (the animals are hemisected) at various times after grafting. Compound heads and compound feet form at the proximal and distal graft borders, respectively, in nearly all 3grp animals. The regeneration of structures at points is a built-in property, not influenced by reversing the polarity of pieces during grafting. Regeneration is accelerated when comparable wound surfaces are brought together by grafting with reversed polarity. Graft rejection is influenced by the total length of an animal and distances from terminal structures, but not the polarity of pieces. Budding is also influenced by total length and distance, but is dependent on polarity and diminished by head regeneration. When fresh wound surfaces are made on the middle piece of 3grp animals, an initial refractory period, during which head and foot (but not budding region) regeneration is inhibited in about half the animals, is followed by an indefinite period in which head and foot regeneration is permitted (and budding region regeneration prevented). Hemisection does not interfere with the regeneration of compound structures already in progress. These results are interpreted in terms of theories of competence, negative dominance, threshold (positional value), inhibition (positional signal), and induction (positive or constructive dominance, stimulation or enhancement).
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Topics: Biology , Medicine
    Notes: Neurosecretory A cells in the pars intercerebralis of O. fasciatus were identified at the ultrastructural level. Fine structural study of the A cells of female insects during the period of production of the first batch of eggs revealed that these cells undergo qualitative and quantitative changes during the first eight days of adult life. The A cells appear to be inactive in the newly emerged females. There is a significant depletion of neurosecretory granules (NSG) in the perikarya in the 2-day-old females followed by an increase and decrease in the 4- and 6-day-old females, respectively. The A cells in the 8-day-old females showed an accumulation of NSG. The mitochondrial population increases after adult emergence reaching a peak in the 4-day-old females, and then declines gradually in the subsequent age groups. The effect of sublethal dose of gamma radiation on the ultrastructure of the A cells was also investigated. Radiation damage is evident as early as four hours after irradiation with 10 kR. There is considerable swelling of the lysosomes and the membrane system in the A cells of irradiated insects. Synthetic activity of the A cells, based on the distribution of the endoplasmic reticulum, Golgi complex and mitochondria, as well as release of the NSG are apparently inhibited after irradiation. Radiation-induced damage becomes more conspicuous as post-irradiation interval increases. It is surmised that the damage to the A cells might have contributed at least in part, to the failure of yolk deposition in the irradiated insects.
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  • 29
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    Journal of Morphology 154 (1977), S. 133-145 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The junction between human primary dentine and regular and irregular secondary dentine was examined with a number of different light and electron microscopic techniques. In decalcified material, a narrow band along the innermost surface of the primary dentine stained intensely. The walls of the tubules within the band stained intensely, whereas the tubular walls within the bulk of the primary dentine were not stained. Generally, the walls of the tubules in both types of secondary dentine were also preferentially stained. Although not readily apparent in ground sections, observations of thin sections revealed a dramatic reduction in the number of tubules in regular secondary dentine. Generally, the radiodensity of the intertubular matrix was the same in primary and secondary dentine and the intensely stained band was not seen radiographically. The pulpal ends of the tubules in primary dentine were often occluded with a material having the same radiodensity as peritubular matrix. Both patent and occluded tubules were seen in irregular secondary dentine. Scanning electron microscopy of acid-etched specimens of secondary dentine revealed that some tubules had irregular walls of highly mineralized matrix which was less acid-soluble than the peritubular matrix of primary dentine.
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  • 30
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    Journal of Morphology 154 (1977), S. 427-458 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Simultaneous cine and electromyographic records of freely feeding, unanesthetized golden hamsters show that their motion and muscular activity during mastication differ from those of albino rats (Weijs, '75). Rats show only propalinal motion while hamsters show lateral translation as well. The masticatory muscles of hamsters and rats are generally similar, but their molar dentitions differ. The interlocking molar cusps of hamsters restrict propalinal protrusion and retrusion when the molars are in occlusion; however, hamsters readily unlock occlusion by a twisting movement in the horizontal plane. Rats may perform propalinal movements even with the teeth in occlusion.In mastication the hamstery's jaw moves laterally as well as vertically and anteroposteriorly. Chewing orbits typically reverse after one to three orbits. Reversal begins at the start of the upstroke and involves a lateral shift in the opposite direction with the mouth closed.Electromyograms show that symmetric and asymmetric activities of closing protrusive and closing retrusive muscles produce a unilateral force couple on both sides. (This couple accompanies a midline closing stroke.) When the mouth is closed, unilateral activity of closing retrusors and closing protrusors also induces lateral translation. A bilateral force couple pits the retrusors of one side against the protrusors on the opposite side. Simultaneous with lateral excursion to the opposite side of midline and the action of these closing muscles, the anterior digastric and lateral pterygoid muscles of one side fire asymmetrically.The mandible moves downward coincidently with bilateral activity of the digastrics and lateral pterygoids. As the jaw opens further, activity differences of the lateral pterygoids accompany a shift of the mandible toward midline. At the end of the downstroke, all masticatory muscles studied are silent. The jaw returns to midline when the adductors fire asymmetrically at the start of closing.Trituration appears to coincide with an initial simple protrusion, which is subsequently accompanied by lateral translation. Different food types are reduced by distint chewing patterns with the differences clearest when the teeth are near occlusion. During gnawing the lateral pterygoids and digastrics fire longer, and the closing muscles fire less strongly. Chewing patterns in golden hamsters appear more generalized than those of rats; the differences may be directly associated with the ability of hamsters to store food in their cheek pouches.
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    Notes: Females of the marbled salamander, Ambystoma opacum, store sperm in exocrine glands called spermathecae in the roof of the cloaca. Eggs are fertilized by sperm released from the spermathecae during oviposition. Some sperm remain in the spermathecae following oviposition, but these sperm degenerate within a month and none persists more than 6 mo after oviposition. Thus, sperm storage between successive breeding seasons does not occur. Apical secretory vaculoes are abundant during the fall mating season and contain a substance that is alcian blue+ at pH 2.5. Production of secretory vacuoles decreases markedly after oviposition, and the glands are inactive by the summer months. Ambystoma opacum is a terrestrial breeder, and some mating occurs prior to arrival at pond basins where oviposition occurs. Mating prior to arrival at the ovipository site may prolong the breeding season, leading to fitness implications for both males and females. Females have opportunities for more matings, and the possibilities for sperm competition in the spermathecae are enhanced. © 1995 Wiley-Liss, Inc.
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: Alcichthys alciocornis has a viscous ovarian fluid in the ovarian cavity, which plays an important role in its unique mode of reproduction called internal gametic association (i.e., internal insemination and sperm-egg association but a delay in the physiological fertilization until spawning). Seasonal changes in fine structure of the inner epithelial lining and capillary endothelium of the ovary revealed that ovarian fluid originated as a result of the secretory activity of the tissues. The ovarian cavity of A. alcicornis is lined with an ovigerous lamella epithelium and an ovarian wall epithelium. During the spawning period, both epithelia actively secreted proteinaceous substances which seemed to constitute the ovarian fluid. The substances appear to be synthesized in the rough-surfaced endoplasmic reticulum from the material which was transported from the blood capillary, taken into the epithelial cells by endocytosis, accumulated in secretory vesicles via Golgi apparatus in the cells, and finally released into the ovarian cavity by exocytosis. Microapocrine secretion was also observed to occur in both epithelia. Secretory activity of both epithelia by exocytosis and microapocrine secretion showed distinct seasonal changes. Active exocytosis and microapocrine secretion were observed during the spawning period (April-May). These activities slightly declined during the degeneration period (May-June) and were lost during the early recovery period (July). During the mid to late recovery period (October-March), there was some exocytosis but no microapocrine secretion. © 1995 Wiley-Liss, Inc.
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  • 33
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    Journal of Morphology 223 (1995), S. 167-174 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cell surface morphology of hamster decidual cells isolated from day 8 implantation swellings was studied, using both phase-contrast and scanning electron microscopy. Two kinds of cells, fibroblastic and epithelioid, were identified in cultures examined by phase-contrast microscopy. Fibroblastic cells were spindle-shaped, having pointed or blunt terminals on one end and bifid or webbed projections at the other end. Epithelioid cells, on the other hand, were flat and discoid, having a distinctively ruffled plasma membrane. Further, the plasma membrane of epithelioid cells formed rope-like or flange-like processes. The significance of such adaptations is discussed. © 1995 Wiley-Liss, Inc.
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    Journal of Morphology 223 (1995), S. 149-166 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This study investigates the effect of developmental stage on thyroid hormone (TH)-mediated remodeling in the skeletal tissues of hemidactyliine plethodontid urodeles. Rate of morphogenesis was quantified in 17 metamorphic tissues for three different size-age classes of Eurycea bislineata larvae immersed in a metamorphic dosage of T4. Extent of morphogenesis after a 3-week immersion was also quantified in these tissues plus four larval ones for the full size range of E. bislineata larvae and for less complete size ranges of E. wilderae, E. longicauda guttolineata, Gyrinophilus porphyriticus, and Pseudotriton ruber larvae. Although all tissues respond more slowly with decreasing size/age, two tissue-specific effects are evident in all species. Larval ossifications are less inducible than metamorphic ossifications, and progressive metamorphic events are more retarded and, in some cases, more prone to abnormal morphogenesis than regressive ones. The first effect agrees with the prediction that tissues that naturally remodel at metamorphosis are more responsive to a metamorphic dosage of TH than those that respond at a larval stage and lower TH. The second effect agrees with the prediction that progressive morphogenesis is more likely to be impaired at small size than regressive morphogenesis, although the frequent discrepancies between individuals of similar size implicate developmental age more than size in this effect. Collectively, these two effects provide only equivocal support for the hypothesis that direct development in plethodontids evolved via precocious TH activity. However, the unexpected transition from ceratobranchial replacement to ceratobranchial shortening in medium-sized larvae suggests that the former pathway requires a longer period of cell specification at low TH. Since ancestral plethodontids appear to have been distinguished by an exceptionally long larval period with exceptionally low TH activity, this developmental prerequisite may in turn be partly responsible for their singular evolution of ceratobranchial replacement. © 1995 Wiley-Liss, Inc.
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    Journal of Morphology 223 (1995), S. 203-214 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The sagittal otolith of Hyperoglyphe antarctica (Centrolophidae: Teleostei) has a prismatic structure in which the anti-sulcal growth axes of each prism consist of a series of nested cones each composed of a mineral layer followed by an organic matrix layer. Broken sections show the mineral layers to be composed of stacks of crystals. Otolith matrix that has been decalcified and air-dried, or critical-pont-dried, retains a periodic structure of repeating high and low matrix density. At high magnifications, both broken whole crystal surfaces and decalcified matrix surfaces have a granular structure. Chloroxbleached whole otoliths also show a granular crystalline structure. At higher magnifications, the air-dried matrix showed a parallel fiber structure with similar dimensions to keratin fibers. © 1995 Wiley-Liss, Inc.
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  • 36
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    Journal of Morphology 223 (1995), S. 191-201 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Ultrastructural descriptions of the dipnoan heart are lacking. Many ultrastructural features of the heart of the Australian lungfish, Neoceratodus forsteri, resemble those of other lower vertebrates. The epicardial cells appear to be adapated for the exchange of material with the pericardial fluid. The most prominent features of the endocardial cells are numerous moderately electron-dense vesicles found within the cytoplasm. These organelles might have an endocrine function. The myocardiocytes are typically small. The banding pattern of the sarcomere is shared with most fish. The intercalated disc has a convoluted path and consists of desmosomes and fascia adherens. Caveolae are a prominent feature of the sarcoplasm. The sarcoplasmic reticulum is sparse, and T-tubules are lacking. Atrial myocardial dense bodies occur in vast numbers throughout the atrium and are occasionally seen in the ventricle. These vesicles are chromaffin-positive but fail to show catecholamine fluorescence. They are likely to contain peptides related to ANP. Subendothelial cells exhibiting catecholamine-specific fluorescence are scattered throughout the atrium. Ultrastructurally these cells contain many chromaffin-positive granules. Chromaffin cells represent another cell type with a probable endocrine function within the heart of N. forsteri. © 1995 Wiley-Liss, Inc.
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    Journal of Morphology 223 (1995) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 38
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    Journal of Morphology 223 (1995), S. 263-268 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A complex of lymphoepithelial organs, the “anal tonsils,” is a consistent structure in the anal canal of the bottlenose dolphin, Tursiops truncatus. This complex occurs as a circumferential cluster of discrete tonsil like aggregations of lymphoid tissues, together with epithelial ducts (“crypts”) and occasional mucus secretory units in the extreme lower portion of the intestinal tract. These structures are concentrated in the segment lined by stratified squamous epithelium and extend for a variable distance cephalad from the anal aperture. The tonsils appear to be most active, judged by the amount of lymphoid tissue present, in young animals. Depletion of lymphocytes and cystic enlargement of the crypts, probably representing functional as well as morphological involution, is a consistent feature of older animals. © 1995 Wiley-Liss, Inc.
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  • 39
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    Journal of Morphology 223 (1995), S. 269-287 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The prenatal development of epidermis, dermis, and hypodermis was studied in embryos of different ago of two delphinid species (Stenella attenuata, Delphinus delphis), using light and transmission electron microscopical methods. The delphinid embryo is covered by a multilayered tissue formed by four different epidermal generations (periderm, stratum intermedium-I, str. intermedium-II, str. spinosum) produced by the str. basale. The first layer appears at about 40-50 mm of body length, the second type (s.i.-I) about 60-160 mm, and the third type (s.i.-II) is present at 160-500 mm. The first spinosal cells are produced at 225-260 mm body length; thenceforth, the epidermis increases continuously in thickness. Epidermal ridge formation begins about 400-mm body length. The development of the dermis is characterized by the early production of thin connective tissue fibers (40- 70-mm body length) and simultaneously the cutaneuous muscle matures in structure. Vascular development intensifies between embryos of 150-225 mm, and collagen production increases markedly in fetuses of 225-260-mm length. These events are paralledled by an increase in dermal thickness. The first elastic fibers can be recognized in the skin from the abdomen at about 600-mm body length. The development of the hypodermis is marked by very rapid and constantly progressing growth, beginning about 60-mm body length. The first typical fat cells appear in animals of 360-400 mm. Regional differences are obvious for all skin layers with regard to the flippers, where structural maturation proceeds more rapidly than in dorsal or abdominal regions. © 1995 Wiley-Liss, Inc.
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  • 40
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    Journal of Morphology 223 (1995), S. 289-302 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Functional comparative morphology of predatory legs in five species of water bugs (Ilyocoris cimicoides, Nepa cinerea, Ranatra linearis, Notonecta glauca, and Gerris lacustris) has been investigatd adn the following peculiarities of leg design were revealed.1Subcoxal articulation may be monoaxial (G. lacustris, N. glauca), or, in contrast to walking leg type, biaxial (N. cinerea, R. linearis, I. cimicoides); the first axis is oriented along the coxa (torsion axis), the second one is perpendicular to the first (non-torsion axis).2In contrast to walking leg type, which is characterized by cross suspension of the axis of coxal rotation in thoracal skeleton, this axis in G. lacustris is placed vertically. Non-torsion coxal axis in R. linearis is oriented strongly transversal. This axis directs the leg strike forward.3Legs in the majority of species are planar: Torsion axes of the coxa, femur, and tibia are placed in the same plane. Axes of rotation of consequent joints in I. cimicoides are reciprocally sloped. Therefore, the end of the leg outlines the spiral trajectory, when all angles of joints are opening (closing). This is an adaptation for clinging to the stems of water plants.4Passive adduction of the femur in the trochanter-femoral joint in N. glauca allows it to go around protuberances of the body wall, when the leg is sliding along them; recurrent femur movement during releasing from the obstacele is active due to the rt.fe muscle.5Only R. linearis has predatory legs, which permit the high-speed pursuit of potential prey; other species realize this function using the swimming legs, whereas the forelegs are used for the manipulation movements.6Muscle arrangement in the prothorax of different species reflects both leg construction and constructional constraints of body design. Powerful flexor muscles (co1, co2, co3, co5, fl.ti, et.ti in R. linearis; fl.ta, fl.ti in N. glauca; fl.ti in I. cimicoides) have long tendons and short muscle bundles, which originate on the leg wall. As a result, the powerful force is developed along the muscle tendon.7Some features of the predatory leg are common for the species studies: elongation of coxae, thickening of femora, and increase of the degree of junction of tibia and tarsus. The muscles, which move the distal segment of the leg, are reinforced and the sclerite of the fl.ti tendon is enlarged. The joint angle of the distal segment is increased to 120°. © 1995 Wiley-Liss, Inc.
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  • 41
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    Journal of Morphology 223 (1995), S. 341-355 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Piranhas, like many teleosts, change their diets on both ontogenetic and phylogenetic time scales. Prior studies have suggested that pervasive morphological changes in body form on a phylogenetic time scale may be related to changes in diet, but previous reports have found little shape change in piranhas on an ontogenetic time scale. We re-examine the post-transformational allometry of body form in one piranha, Pygocentrus nattereri (Kner), using the method of thin-plate splines decomposed by their partial warps. We find substantial evidence of allometry, primarily elongation of the mid-body relative to the more anterior and posterior regions, elongation of the postorbital and nape regions relative to the more anterior head and posterior body, and deepening of the head relative to the body. In addition to these pervasive changes throughout the body, there are some that are more localized, especially elongation of the postorbital region relative to eye diameter and snout, and an even more localized elongation of the snout relative to eye diameter. Initial dietary transitions are associated with changes in head and jaw proportions, but rates of shape change decelerate through growth, so that the final transition to a diet increasingly dominated by small whole fish appears associated with change largely in overall body size. © 1995 Wiley-Liss, Inc.
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    Journal of Morphology 224 (1995), S. 87-96 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Muscles in the body wall, intestinal wall, and contractile hemolymphatic vessels (pseudohearts) of an oligochaete anelid (Eisenia foetida) were studied by electron microscopy. The muscle cells in all locations, except for the outer layer of the pseudohearts, are variants of obliquely striated muscle cells. Cells comprising the circular layer of the body wall possess single, peripherally located myofibrils that occupy most of the cytoplasm and surround other cytoplasmic organelles. The nuclei of the cells lie peripherally to the myofibrils. The sarcomeres consist of thin and thick myofilaments that are arranged in parallel arrays. In one plane of view, the filaments appear to be oriented obliquely to Z bands. Thin myofilaments measure 5-6 nm in diameter. Thick myofilaments are fusiform in shape and their width decreases from their centers (40-45 nm) to their tips (23-25 nm). The thin/thick filament ratio in the A bands is 10. The Z bands consist of Z bars alternating with tubules of the sarcoplasmic reticulum. Subsarcolemmal electron-dense plaques are found frequently. The cells forming the longitudinal layer of the body wall musculature are smaller than the cells in the circular layer and their thick filaments are smaller (31-33 nm centrally and 21-23 nm at the tips). Subsarcolemmal plaques are less numerous. The cells forming the heart wall inner layer, the large hemolymphatic vessels, and the intestinal wall are characterized by their large thick myofilaments (50-52 nm centrally and 27-28 nm at the tips) and abundance of mitochondria. The cells forming the outer muscular layer of the pseudohearts are smooth muscle cells. These cells are richer in thick filaments than vertebrate smooth muscle cells. They differ from obliquely striated muscle cells by possessing irregularly distributed electron-dense bodies for filament anchorage rather than sarcomeres and Z bands and by displaying tubules of smooth endoplasmic reticulum among the bundles of myofilaments. © 1995 Wiley-Liss, Inc.
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  • 43
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Topics: Biology , Medicine
    Notes: In this report, the gonads of 32 glandulocaudine species, representing 18 genera, are compared with 11 outgroup characiform species. Through the presence of spermatozoa within the ovarian cavity, internal fertilization of the female is confirmed for the 16 genera for which mature ovaries were available. No outgroup ovary studied contains spermatozoa. All mature glandulocaudine testes have a large portion of the posterior testis, which is devoid of developing germ cells and spermatocysts (aspermatogenic), devoted to sperm storage, with the degree of partitioning in that region varying greatly within the group. All outgroup species examined have spermatozoa with spherical nuclei. With the exception of the species of the genus Planaltina, which also have spherical nuclei, all glandulocaudines have elongated nuclei, which vary among the species from 3.6 μm to 31.6 μm in length. Distinct sperm packets (spermatozeugmata) are formed in five genera by two different methods. In the genera Xenurobrycon, Tyttocharax, and Scopaeocharax, all of the tribe Xenurobryconini, the spermatozeugmata are formed within the spermatocysts and released fully formed. In all genera of the tribe Glandulocaudini, which includes Glandulocauda and Mimagoniates, loose spermatozoa are released which cluster into spermatozeugmata within the posterior storage areas. These morphological specializations are discussed within a phylogenetic framework as adaptations for internal fertilization and are hypothesized to be independently derived. © 1995 Wiley-Liss, Inc.
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  • 44
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    Journal of Morphology 224 (1995), S. 199-203 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Interdigitating cells in the thymus of the sea bass, Dicentrarchus labrax, occur principally in the internal zone and in the border with the external zone. Ultrastructurally, the most characteristic cytological features of these cells are their low electron density, complicated labyrinthine membrane-membrane contacts, scantiness of cytoplasmic organelles, presence of Birbeck-like granules, juxtanuclear tubulo-vesicular complex, and phagocytic capacity. © 1995 Wiley-Liss, Inc.
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Morphological and ultrastructural features of the salivary glands and proboscises of Placobdella ornata, Placobdella parasitica, and Desserobdella picta were studied by light and electron microscopy. Chemical composition of the salivary cells was investigated using a variety of histochemical techniques. Placobdella ornata and P. parasitica have compact salivary glands with discrete pairs of anterior and posterior glands, while the salivary cells contain one mucous and three proteinaceous secretions. Salivary glands of D. Picta are diffusely arranged and contain two mucous and two proteinaceous secretions. A cobalt-lysine forward-filling technique revealed that individual salivary cells consist of a roughly spherical soma and an elongated ductule. The majority of the internal space in a salivary soma is densely packed with spherical secretory granules which displace the cytoplasm to the periphery of the cell. Bundles of individual ductules enter the base of the proboscis on opposite sides and extend anteriorly. The ductules, also packed with secretory granules, are surrounded by microtubules associated with agranular endoplasmic reticulum, and merge with deep invaginations of the proboscis cuticle. The secretory granules are released at the end of these invaginations or pores. Pores were found on the tip, along the body, and on the luminal wall of the proboscises in all three species. © 1995 Wiley-Liss, Inc.
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  • 46
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    Journal of Morphology 225 (1995), S. 61-75 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Longitudinal and principal strain recordings were made in vivo at three sites (dorsal, anterior, and ventral) on the humeral midshaft of pigeons executing five modes of free flight: Take-off, level flight, landing, vertical ascent, and near-vertical descent. Strains were also recorded while the birds flew carrying weights that were 33%, 50%, or 100% of their body weight. The relative distribution of strain measured at the three surface midshaft sites and across the bone's cortex was found to be similar for all flight modes. Principal strains recorded in the dorsal and ventral humerus indicated considerable torsion produced by aerodynamic loading of the wing surface posterior to the bone. Measured torsional shear strains (maximum: 2,700-4,150 μ ε during level flight) were 1.5 times greater than longitudinal strains. In addition to torsion, the humerus is also subjected to significant dorsoventral bending owing to lift forces acting on the wing during the downstroke. Analysis of the cross-sectional distribution of longitudinal strains at the humeral midshaft cortex shows that the orientation of bending shifts in a regular manner during the downstroke, indicating that the wing generates progressively more thurst (vs. lift) later in the downstroke. This shift is less during take-off and vertical ascent when greater lift is required. Peak principal and longitudinal strains increased by an average of only 50% from landing to vertical ascending flight and take-off (e.g., dorsal humerus: -1,503 to -2,329 μ ε) and did not exceed -2,600 μ epsiv; at any site, even when the birds flew carrying twice their body weight. Strains recorded when birds flew at two times their body weight (100% BW load) were similar in magnitude to those recorded during vertical ascent and take-off and likely represent those developed during maximal performance. Strains developed within the midshaft were maximal in the anterodorsal and posteroventral cortices, not at the dorsal, ventral, and anterior sites at which strain was recorded. Consequently, maximum strains experienced by the bone are probably 20-25% greater than those recorded (ca. 3,200 μ ε), indicating a safety factor of about 3.5 for compressive strain failure. The much higher shear strains, however, indicate a lower safety factor (1.9), in which the bone's torsional strength is its most critical design feature. Finally, the magnitude and distribution of strains developed in the humerus of pigeons are generally similar to those recorded in the humerus of large fruit-eating bats during flight. © 1995 Wiley-Liss, Inc.
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  • 47
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    Journal of Morphology 225 (1995), S. 107-123 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cephalometry was used to detect patterns of cranial growth in fetal bats that were stained differentially for bone and cartilage. Three developmental features distinguish embryos of taxa that echolocate nasally from embryos of taxa that echolocate orally: (1) the basicranium is retained ventral to the cervical axis, (2) the rostrum is retained below the basicranial axis, and (3) the lateral semicircular canals are rotated caudally. Together, the first two actions align the fetal nasal cavity with what will be the long axis of the adult body in flight. The third action aligns the lateral semicircular canals with the horizontal. In contrast, skulls of oral-emitting taxa are constructed such that the oral cavity is aligned with the long axis of the body in flight. The evolution of head posture and skull form in microchiropteran bats has been constrained by the demands of vocalization, i.e., ultrasonic echolocation. Accordingly, the ontogeny of the microchiropteran skull has been canalized along two distinct developmental paths - oral-emitting and nasal-emitting Baupläne. © 1995 Wiley-Liss, Inc.
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    Journal of Morphology 225 (1995) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 49
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    Journal of Morphology 225 (1995), S. 251-260 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Assulina muscorum secretes morphologically altered shells when cultured in a medium with 5 mM caffeine. The siliceous scales, normally distributed in a regular overlapping pattern, are disorganized, thicker and wider than normal, and occasionally have incompletely silicified surfaces that appear irregular in profile in transmission electron microscopic ultrathin sections. The shape of the silica deposition vesicles (SDVs) in the cytoplasm is altered and they are less regularly arranged. The swollen appearances of the SDVs, and of nearby Golgi tubules, give additional evidence that caffeine affects the fine structural morphology of membranous secretory organelles and can disrupt their normal depositional activity. In addition to the greater thickness and width of the siliceous scales in caffeine-treated cells, the length and width of the shell are larger compared to controls, but the aspect ratio (length / width) is smaller. The latter is attributed to a larger increase in width relative to the increase in length of the caffeine-reated cells. Since some of the scales are deposited with the long axis laterally on the shell surface, in addition to being greater in width, this raises the interesting question of whether the morphology of the SDVs and the siliceous products influences the size and morphogenesis of the shell. Further research is needed to clarify the interaction of the SDVs with the cytoplasmic cytoskeletal system during shell morphogenesis. © 1995 Wiley-Liss, Inc.
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Topics: Biology , Medicine
    Notes: This study deals with some macroscopical, microscopical, and ultrastructural aspects of the spinal cord central canal of the German shepherd dog. The caudal end of the spinal cord is constituted by the conus medullaris, which may extend to the first sacral vertebra, the terminal ventricle, and the filum terminale. The latter structure is considered as internum (second to third sacral vertebrae) or externum (fifth caudal vertebra), according to its relation to the dura mater. Occasionally, there is a second anchorage which is close to the level of the sixth caudal vertebra. The central canal is surrounded by a ciliated ependymal epithelium, which differs depending upon the levels. The most caudal part of the filum terminale bears a columnar ciliated ependymal epithelium surrounded by two layers of glia and pia mater, which separate the central canal from the subarachnoid space. Microfil injections show a communication between the cavity and the subarachnoid space, as the plastic is able to pass through the ependymal epithelium. At the level of the terminal ventricle there are real separations of the ependymal epithelium, which seem to connect the lumen of the spinal canal with the subarachnoid space. These structures probably constitute one of the drainage pathways of the cerebrospinal fluid. The diameter of the central canal is related to the age of the animal. However, even in very old animals the spinal cord central canal reaches the tip of the filum terminale and remains patent until death. At the ultrastructural level the ependymal cells present villi, located on cytoplasmic projections, cilia, dense mitochondria, and oval nuclei. © 1995 Wiley-Liss, Inc.
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    Journal of Morphology 224 (1995), S. 179-198 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Female reproductive tracts of the viviparous neo-tropical onychophoran Peripatus acacioi have been examined at different times throughout the year, and the altering relationship between the developing embryo and the uterus is described. Depending on her age and time of year, the female may have one or two generations of embryos within her uterus. The uterine wall consists of a thin outer epithelium and basal lamina, three layers of muscles, and a thick basal lamina beneath an inner epithelium lining the uterus lumen. These layers are consistent along the length of the uterus apart from the inner epithelial lining, which varies according to position in the uterus and the developmental stage of embryos contained in the uterus. Early embryos are positioned along the length of the uterus and therefore have space in which to grow. During cleavage and segment formation, each embryo is contained within a fluid-filled embryo cavity that increases in size as the embryo grows. Morulae and blastulae are separated by lengths of empty uterus in which the epithelial lining appears vacuolated. Until the process of segment formation is complete, the embryos are attached to a placenta by a stalk and remain in the same part of the upper region of the uterus. As these embryos grow, the lengths of vacuolated cell-lined uterus between them decrease. Each embryo cavity is surrounded by the epithelial sac, the maternal uterine epithelium, which becomes overlaid by a thin layer of cells, the embryo sac, which is believed to be of embryonic origin. The placenta is a syncytial modification of the epithelial sac located at the ovarian end of each embryo cavity covered by the embryo sac and is analogous to the mammalian noninvasive epitheliochorial placenta. Segment-forming embryos have their heads directed toward the ovary. As the embryo gets longer during segment formation, its posture changes from coiled to flexed. Once segment formation is complete, the embryo loses contact with its stalk, an embryonic cuticle forms, and the embryo turns around so that its head is directed toward the vagina. The embryo escapes from its embryo sac and moves to the lower part of the uterus. In the lower part of the uterus, the straightened fetuses are first unpigmented but subsequently become pigmented as the secondary papillae on the body surface form and an adult-type cuticle forms beneath the embryonic cuticle. While the embryos are contained within their embryo cavities, nutrients are supplied by the placenta. Throughout development the mouth is open and in the mature fetus the gut is lined by peritrophic membrane and material is present in the gut lumen. Trachea have been observed only in fetuses that were ready for birth. Insemination, cyclical changes in the uterine epithelium, and the nature of the cuticle shed at parturition are discussed. © 1995 Wiley-Liss, Inc.
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    Journal of Morphology 225 (1995), S. 91-105 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The supporting elements of the avian propatagium were examined in intact birds and as isolated components, using static force-length measurements, calculated models, and airflow observations. The propatagial surface supported between Lig. propatagiale (LP) and brachium-antebrachium is equally resistant to distortion over the range of wing extension used in flight. The lengths LP assumes in flight occur across a nearly linear, low-stiffness portion of the force-length curve of its extensible pars elastica. In an artificial airflow, intact wings automatically extend; their degree of extension is roughly correlated with the airflow velocity. Comparisons between geometric models of the wing and the passive force-length properties of LPs suggest that the stress along LP blances the drag forces acting to extend the elbow. The mechanical properties (stiffness) of the LP vary and appear to be tuned for flight-type characteristics, e.g., changes in wing extension during flight and drag. Lig. limitants cubiti and LP combine to limit elbow extension at its maximum, a safety device in flight preventing hyperextension of the elbow and reduction of the propatagium's cambered flight surface. Calculations using muscle and ligament lengths suggest that M. deltoideus, pars propatagialis, via its insertions onto both the propatagial ligaments, controls and coordinates propatagial deployment, leading edge tenseness, and elbow/wing extension across the range of wing extensions used in flight. The propatagial ligaments and M. deltoideus, pars propatagialis, along with skeleto-ligamentous elbow/carpus apparatus, are integral components of the wing's extension control mechanism. © 1995 Wiley-Liss, Inc.
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    Journal of Morphology 225 (1995), S. 125-167 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A new approach to devising embryological staging systems allows improved phylogenetic comparisons of developmental patterns. As in traditional approaches, morphological features provide the defining criteria for stages, but unlike traditional normal tables, each stage is defined by no more than one or two morphological criteria that are fundamental developmental features of all teleosts. Additional developmental features that occur concurrently with the defining criteria of a stage are treated as variables potentially uncoupled from the defining criteria for that stage. This system is well suited to detect phylogenetic heterochrony and promises to increase our understanding of conserved vs. labile features in teleostean embryology. In this study, I explain the defining criteria for American shad and then make comparisons with other clupeoids. The development of American shad includes 35 stages extending from fertilization to metamorphosis. Comparisons with other clupeoids indicate that the developmental pattern of shad is representative of the early ontogeny of many clupeoids during the embryonic and yolk sac periods and may be conservative for the group. However, several concurrent features, particularly hatching, formation of neuromasts, and opercular development, vary in developmental timing among clupeoids. Comparisons indicate that shad embryos delay the development of these concurrent features relative to other clupeoids. Modifications of the developmental pattern for different species of clupeoids are heterochronic but their phylogenetic and adaptive significance is unknown. © 1995 Wiley-Liss, Inc.
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    Journal of Morphology 225 (1995), S. 193-211 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A description is provided of the fiber-type composition of several hindlimb muscles of the adult turtle, Pseudemys (Trachemys) scripta elegans. In addition, cross-section areas of each fiber type and an estimation of the relative (weighted) cross-section area (wCSA) occupied by the different fiber types are also provided. Seven muscles were selected for study, based on their suitability for future neurophysiological analysis as components of the segmental motor system, and on their homologies with muscles in other vertebrates. The test muscles were iliofibularis (ILF), ambiens (AMB), external gastrocnemius (EG), extensor digitorum communis (EDC), flexor digitorum longus (FDL), tibialis anterior (TA), and peroneus anterior (PA). Serial sections of these muscles were stained for myosin adenosine triphosphatase (ATPase), NADH-diaphorase, and alpha-glycerophosphate dehydrogenase (α-GPDH), thereby enabling fiber-type classification on the basis of indirect markers for contraction speed and oxidative (aerobic) vs. glycolytic (anaerobic) metabolism. All muscles contained three fiber types: Slow oxidative (SO; possibly including some non-twitch tonic fibers); fast oxidative glycolytic (FOG); and fast glycolytic (Fg). There were at least 30% FOG and 50% FOG + Fg fibers in the seven muscles, the extreme distributions being the predominantly glycolytic ILF vs. the predominantly oxidative FDL muscle (ILF - 15.5% SO, 35.2% FOG, 49.3% Fg vs. FDL - 49.1% SO, 41.1% FOG, 9.8% Fg). As in other species, the test muscles exhibited varying degrees of regional concentration (compartmentalization) of the different fiber types. This feature was most striking in ILF. Pronounced compartmentalization was also observed in AMB, EG, PA, TA, and EDC, whereas the distribution of fiber types in the highly oxidative FDL was homogeneous. In five of the seven muscles, fiber size was ranked with Fg 〉 FOF 〉 SO. In terms of wCSA, which provides a coarse-grain measure of the different fiber types' potential contribution to whole muscle peak force, all muscles exhibited a higher Fg and lower SO contribution to cross-section area than suggested by their corresponding fiber-type composition. The largest relative increases in wCSA vs. fiber-type composition were in the ILF and AMB muscles. We conclude that the turtle hindlimb provides some interesting possibilities for testing for a division of labor among different muscles during different movements (e.g., sustained vs. ballistic), and for study of the behavior of the different fiber (and motor unit) types under normal and perturbed conditions. The relationships between the present results and previous findings on homologous muscles of the mammalian (cat, rat) and reptilian (lizard) hindlimb are discussed. © 1995 Wiley-Liss, Inc.
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    Journal of Morphology 225 (1995), S. 261-268 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: During the breeding season, the terminal end of the ductus deferens of Calotes versicolor appears swollen and is comparable to the ampulla of the mammalian ductus deferens. Its anatomy was studied from paraffin sections. It differentiates along its length into five zones. The first has thick smooth muscle and pesudostratified epithelium; the second has luminal trabeculae with an epithelium showing evidence of secretory activity; the third has the epithelial mucosa abutting against the smooth muscle in the form of pocketlike indentations; the fourth has crypts between epithelial folds; and the fifth zone is a sphincter. The anatomy of this ampullary region is indicative of secretory as well as spermatophagous roles. It undergoes seasonal change and appears to be androgen-dependent. © 1995 Wiley-Liss, Inc.
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    Journal of Morphology 225 (1995), S. 357-367 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: Endothermic heat production and the capacity to shiver develop soon after hatching in birds, permitting chicks to regulate their body temperature. Physiological studies have not clearly identified the developmental events causing this change in function. Here, we use electron microscopy to examine the development of structures involved in muscle activation, contraction, and metabolism coincident with the development of shivering thermogenesis. A stereological study was used to compare the ultrastructure of chicken iliofibularis before endothermic heat production was present (24 h before hatching) and 120 h later, when the iliofibularis had substantial capacity for shivering. Profound increases were found in the t-tubule system and terminal cisternae, mitochondrial cristae, and lipids. The number of triadic profiles increased 3.8-fold (7.6 ± 1.31/100 μm2 to 28.5 ± 2.90/100 μm2 fiber area). The surface area of cristae per mitochondrial volume doubled (12.0 ± 1.50 pm2/pm3 to 25.7 ± 1.84 μm2/μm3). Lipid droplets were rare in the iliofibularis of embryos about to hatch, but accounted for 4.4% of the muscle fiber volume in day 4 birds. We suggest that these ultrastructural changes more fully activate the iliofibularis, allow it to produce more heat both from calcium pumping and from contraction, and increase its endurance, thus permitting the muscle to be effective in thermogenesis. © 1995 Wiley-Liss, Inc.
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    Journal of Morphology 226 (1995) 
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    Journal of Morphology 226 (1995), S. 25-31 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Topics: Biology , Medicine
    Notes: Five types of sensilla are situated on the apical area of the labial and maxillary palpi and galea of Cicidela sexguttata. Large, conical, and peg-like sensilla are in rows on the central region of each palpus. These sensilla have a hollow cuticular peg, with an apical pore and multi-innervation. This central region of palpal sensilla is surrounded by campaniform sensilla that are disc-shaped and small conical peg sensilla. A similar type of conical sensillum as the found in the palpal central region is situated around the periphery of the palpal apex and apex of the galea. This conical peg sensillum is located in a shallow depression and is structurally similar to the other peg sensilla, but it has a mechanoreceptor neuron attached to the cuticular base of the sensillum. A long, single, trichoid sensillum is situated in the center of the galea and is hollow, thick-walled, porous, and multi-innervated. The apices of the palpi and galea have a large number of dermal gland openings that actively secrete a substance during the feeding process of the tiger beetle. © 1995 Wiley-Liss, Inc.
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    Notes: Changes in ovarian histology during the reproductive cycle of the viviparous lizard Sceloporus torquatus torquatus are described. In general, the variation in follicular histology observed during the seasonal cycle is similar to that of other lizards. Sceloporus t. torquatus exhibits a cycle in which small, previtellogenic follicles exist in the ovary from December to August. Vitellogenesis occurs between September and November, followed by ovulation from late November to early December. Parturition occurs the following spring. After ovulation, the remaining follicular cells form the corpus luteum and luteolysis did not occur until April-May. Follicular atresia is commonly observed in previtellogenic follicles with polymorphic granulosa, but occurs less frequently in follicles during late vitellogenesis. There are two germinal beds in each ovary. The yolk nucleus is evident in young oocytes as is a vacuolated ooplasma prior to vitellogenesis. Extensive polymorphism is observed in yolk platelets. Mast cells and secretory cells are observed in the thecal layer of the follicular wall as are melanocytes in the ovarian stroma. © 1995 Wiley-Liss, Inc.
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    Journal of Morphology 226 (1995), S. 159-171 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Ectoplacental cones isolated from embryos on the seventh day of pregnancy wer transplanted beneath the hepatic capsule of recipeint adult animals to document the morphological patterns of vascular invasion by the trophoblast in the absence of the maternal environment and the influence of its peculiar vasculature. Females, and females and males of Calomys collosus, a cricetid rodent, were used, respectively, as embryo donors and recipient animals. Three to 5 days later, the grafted regions were excised and processed for light and electron microscopy. Invasion of the liver parenchyma by the trophoblast progressed along the vascular beds, associated with gradual phagocytosis of hepatic cells, greatly favoring the morphological characterization of invasive steps exhibited by the trophoblast to access the different kinds of vessels, to trespass the various vascular components and the different levels of the surrounding hepatic parenchyma. It is possible that either in utero during the establishment of embryomaternal circulation in early pregnancy or ex utero under experimental conditions, the trophblast exhibits similar vascular invasion behavior. In view of this, our findings may contribute to a better understanding of trophoblast cell migration to the maternal blood supply as well as the role of the trophoblast in the establishment of the placental circulation during pregnancy. © 1995 Wiley-Liss, Inc.
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    Notes: A commentary is provided on the segmental motor system of the turtle Pseudemys (Trachemys) scripta elegans with an emphasis on neuronal, neuromuscular, and muscular mechanisms that control the development of force under normal, fatiguing, and pathophysiological conditions. For the central neuronal component of the segmental motor system, it has recently been shown that intracellular analysis of the firing properties of motoneurons and interneurons can be undertaken for relatively long periods of time in in vitro slices of the lumbosacral spinal cord of the adult turtle. In other less reduced in vitro preparations, analyses are available on complex motor behaviors generated by the isolated spinal cord. These behaviors of spinal neuronal networks are analogous in key aspects to those generated by the isolated in vivo cord, and by the cord in intact preparations. These results suggest that the neuronal components of the segmental motor system can now be studied from the cellular/molecular level of analysis in in vitro slice preparations to the systems level in conscious, freely moving animals. The in vitro approach can also be used for the analysis of cellular mechanisms in suprasegmental brain structures, which contribute to the control of voluntary movement. For the peripheral neuromuscular component of the segmental motor system, information is now available on muscle fiber types and selected aspects of sensory innervation, and it is feasible to study the mechanical and biochemical properties of motor units. As such, the turtle presents a valuable model for exploring interrelations between the neuronal and mechanical components of the segmental motor system of the generalized tetrapod. A prominent feature of these recent developments is the extent to which they have been deriven by findings that have emphasized an evolutionary conservation of motor-control mechanisms extending from ion channels, at the cellular level, to the control of multijointed movements at the systems level of analysis. © 1995 Wiley-Liss, Inc.
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    Notes: Correlative studies of luminescent responses, light and electron microscopy of Porichthys photophores during development were conducted. The photophores differentiate as an outgrowth of the basal cell layer of the epidermis, from which they delaminate into the dermis. Reflector cells are formed from dermal fibroblasts. Early photophore cells differentiate into three distinct cell types: photocytes, supportive and lens cells. Elaborate profiles of endoplasmic reticulum, Golgi bodies and vesicles suggest intense secretory activity in the early photocytes, while supportive and lens cells differentiate by two different transformations of the microfilament arrangement of primordial photophore cells.Luminescent capabilities of Porichthys photophores arise in two successive phases: (1) an aneural phase during which photophores become fluorescent, photocytes are in process of maturation and respond only to chemical stimulation and (2) a neural phase in which photophores luminesce upon electrical and pharmacological stimulation and are densely innervated with terminals showing relatively narrow neurophotocyte gaps. The presence of neural elements intimately associated with the early photophore anlagen suggests the involvement of the peripheral nervous system in the formation of photophores.
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    Notes: The degree of minced rat muscle regeneration in the absence of nerve fibers was compared with that of normal regenerates between one and 270 days postoperatively. Up to around 30 days, the number of muscle fibers and their morphology were comparable in both normal innervated and denervated regenerates; both showed clear cross striations and peripherally located nuclei. Histochemically, SDH and myofibrillar ATPase (pH = 9.4) reactions were positive, but there were no typical signs of fiber types in either case of regeneration. The only consistent difference in the early period was the smaller fiber cross sectional areas in denervated regenerates than in innervated ones. Starting about 40 days, the muscle fibers in innervated regenerates became differented into different fiber types (fast-twitch-oxidative-glycolytic, FOG., fast-twitch-glycolytic, FG., slow-twitch-oxidative, SO.) but there were no such activities in denervated regenerates, although their SDH and myofibrillar ATPase reactions remained positive for a long time. Degenerating muscle fibers could no longer be identified in innervated regenerates. In the denervated regenerates, however, muscle fibers underwent atrophic or degenerative changes and were replaced by connective tissue. The complete disappearance of muscle fibers varied with individual regenerates. In some cases, it occurred about 90 days and in others, traces of muscle fibers could still be seen as late as 150 days postoperatively. Thus, nerves seem to be important primarily in the late phase of regeneration; namely, differentiation of fiber types and maintenance of the structural integrity of muscle fibers.
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    Journal of Morphology 151 (1977), S. 439-449 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Latero-frontal, para-latero-frontal, and frontal ciliary tracts on the gill filaments of Crassostrea virginica (Gmelin) were studied with light microscopy and scanning electron microscopy. Latero-frontal cirri are complex structures composed of varying numbers of paired cilia. The multiple pairs of cilia which constitute a single cirrus are closely appressed for a portion of their length; they then branch laterally from the central axis in a plume-like fashion. Latero-frontal cirri of adjacent gill filaments create a filtration sieve which should be capable of retaining particles smaller than 1 μm in diameter. Para-latero-frontal cilia are short, closely spaced cilia arranged as a staggered row along the frontal side of each tract of latero-frontal cirri. Latero-frontal cirri and para-latero-frontal cilia occur on ordinary, principal, and transitional gill filaments. Frontal ciliary tracts of ordinary filaments are divided into a central, ventrally directed coarse tract, flanked on either side by a dorsally directed fine ciliary tract. The coarse tract is covered by cirri which are comprised of five to eight cilia, while the fine frontal tracts are made up of individually functioning cilia. The frontal ciliary tracts of principal and transitional filaments bear only dorsally directed fine cilia. The unique direction of effective beat of the coarse frontal cirri of ordinary filaments, in combination with the action of fine frontal cilia and the strategic location of mucus producing cells, is used to describe a possible mechanism for the sorting of filtered particles.
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    Journal of Morphology 151 (1977), S. 463-463 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 66
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    Journal of Morphology 152 (1977), S. 21-53 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The skeletal structure of the stomachs of several decapod Crustacea is described in detail. The general organization of the ossicles is similar for all species and the homologies of the elements can be recognized despite large variations from group to group. The Reptantia are characterized by a complex ossicle organization while the Natantia, on the other hand, are characterized by a simple organization. The various types of ossicle organization found in the decapod stomach can be arranged in a series ranging from simple to complex. The Brachyura have the most complex ossicle system and the Penaeidea the most simplified. This graded series of complexity closely follows the evolution of the Decapoda.
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  • 67
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    Journal of Morphology 152 (1977), S. 1-19 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Records of electrical activity in the tracheal muscles of domestic chickens were obtained for a variety of ad libitum vocalizations. Primary attention was given to an analysis of events during the most complex call, crowing.Three pairs of muscles, Mm. tracheohyoideus, tracheolateralis, and sternotrachealis, can affect the configuration of a chicken's syrinx. The firing patterns of the three muscle pairs are related to their different abilities to affect the tension of the syringeal membranes. The influence of M. tracheohyoideus is most indirect and imprecise, and its role the least clearly defined. It appears to adjust the position of the trachea so that the syrinx is isolated from unpredictable and/or undesirable consequences of nuchal position and tracheal elasticity, and also helps draw the glottis caudad, thereby deepening the pharyngeal chamber. The other two muscles interact to control the tension of the vocal membranes. M. sternotrachealis relaxes the membranes by drawing the drum of the trachea caudad, or, via the syringeal ligament, by rotating the pessulus cranioventrad, or both. M. tracheolateralis tenses the membranes and/or prevents caudal movement of the origin of M. sternotrachealis, a necessity if the syringeal ligament is to rotate the pessulus.Vocalization depends on both syringeal configuration and appropriate air flow. Hence, tracheal muscles, syrinx, air sacs, and ventilatory muscles cooperate to form a vocal system. Cooperation elicits a surprising degree of redundancy. At least one call, a high pitched wail, may be produced by two very different techniques.
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  • 68
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    Journal of Morphology 152 (1977), S. 89-99 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Dissection of the cervical and basicranial regions in three species of snakes indicates that compared to Crotalus viridis and Lichanura roseofusca, Masticophis flagellum possesses relatively high numbers of compound axial muscle insertions on the atlas-axis and vertebrae numbers 3-5. It is suggested that the condition in Masticophis facilitates its vertical-neck-horizontal-head foraging posture and has allowed axial muscles inserting on the dorsocaudal braincase in this snake to generate vertical and lateral head movements more effectively.
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  • 69
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    Journal of Morphology 152 (1977) 
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  • 70
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    Journal of Morphology 152 (1977), S. 101-140 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The osteology of the pectoral limb of small captorhinids is described and figured in detail. A cartilaginous sternum was present. The glenoid was not a simple sliding or rocking joint, as was previously supposed, but considerable rotation was also an integral part of the humeral movement. The structure of the elbow joint is such that when the lower arm was extended, its distal end swung forward and extended the anterior reach of the hand. When the lower arm was flexed, the posterior reach of the hand was extended. Articulated specimens allow a recontruction of the manus. There was no well developed wrist joint, but rather the manus, as a whole, was a flexible structure. A pisiform was present. Sesamoid bones were developed in the tendons of the palmaris communis profundus muscle.Study of forelimb musculature of living reptiles based on dissections and the literature indicates that its evolution has been very conservative. The forelimb musculature of small captorhinids probably was very similar to that of all living reptiles except turtles.
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  • 71
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    Journal of Morphology 152 (1977), S. 153-169 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cochleae (125) from 26 species of the rodent family Heteromyidae (genera Dipodomys. Microdipodops, Perognathus, and Liomys) were compared. In Perognathus and Liomys the scala tympani in the apical portion is extremely narrow with a correspondingly minute helicotrema. In Liomys there is no bone separating scala tympani from spiral ganglion in the upper second and entire third turn. In all species studied the zona pectinata of the basilar membrane is enlarged, with a hyaline mass between upper and lower basilar membrane fibers. This zona pectinata hypertrophy is least at the base of the cochlea and greatest in the upper second turn, decreasing again toward the apex. Basilar membrane width increases rapidly in the first turn and then changes only slightly.Except for Liomys, all the heteromyids studied have hypertrophied Hensen's cells with long apical processes supporting and forming an elevated reticular lamina. These Hensen's cells reach their maximum size in the upper second and lower third turns; throughout they rest on inner Claudius' cells rather than the basilar membrane. Relative to naso-occipital length the cochlear specializations are greatest in Microdipodops and least in Liomys just as is the case for middle ear modifications.The morphological data are consistent with the concept that standing wave phenomena may be important in heteromyid cochlear biomechanics. Single unit data of other workers are also consistent with this interpretation. Like middle ear morphology, inner ear morphology appears adapted to low-frequency sensitivity-especially in Dipodomys and Microdipodops.
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  • 72
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    Notes: The developmental rates of male and female embryos of Xyleborus ferrugineus were compared by charting for each sex the mean age for each of ten discrete morphological stages of embryogenesis from pole cell exclusion to eclosion. Male and female embryos developed synchronously from stage 1 (which begins with pole cell exclusion) through stage 4 (which ends with the completion of germ band extension and metamerization). After stage 4 and throughout the remainder of embryogenesis, the mean ages per morphological stage of male embryos were significantly greater than those for female embryos. The expected physiological consequences of a haploid genome in the male embryo as compared to a diploid condition in the female embryo are discussed as the possible basis for the persistent lag observed in male developmental rate after stage 4.
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  • 73
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    Journal of Morphology 152 (1977), S. 281-302 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The morphology of the chaetae of the maldanid polychaetes Clymenella torquata (Leidy) and Euclymene oerstedi (Claparède) (= Caesicirrus neglectus Arwidsson, '11) are described and related to movements observed in the laboratory. Graphs are constructed of the number and length of the neuropodial chaetae of each chaetiger throughout the body of Clymenella and of species of the genera Euclymene, Macroclymene and Axiothella, and show a characteristic and relatively constant pattern for each species. This work suggests that in making taxonomic decisions, more attention should be paid to the overall pattern of the neuropodial chaetae and less to the confusing distinction between aciculae and rostral uncini.
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  • 74
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    Journal of Morphology 153 (1977), S. 163-185 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Four kinds of neurosecretory cells A, B, U and C are distinguished in the central nervous system of Dendrobaena atheca Cernosvitov. A cells, which show different morphological characteristics under different physiological states and during their cyclic changes, are the most active neurosecretory cells. They form the outer layer of the cortical cell zone in the cerebral ganglion. B cells are large and medium sized and are distributed in all parts of the central nervous system. U cells are found only in the sub-pharyngeal ganglion while C cells are distributed in the sub-pharyngeal as well as in the ventral nerve cord ganglion. The number and secretory activity of C cells decrease in caudal direction. Further, Gomori-positive cells are also observed in the ganglia of the vegetative nervous system.A rudimentary neurohaemal organ, the storage zone, has been observed in the cerebral ganglion and there appears to be another neurohaemal area in the ventral nerve cord ganglion. The storage zone is formed by the terminal ends of the axons of A cells. The chrome alum haematoxylin phloxin (CHP) and aldehyde fuchsin (AF) positive substances in the form of granules are found in this area. The cerebral ganglion is richly supplied by blood capillaries. The distal end of the axons of B cells are swollen like a bulb while in some cases the axons are united to form an axonal tract. Extra-cellular material is abundant in different parts of the nervous system. In all cell types, the perinuclear zone is the first to show activity in the secretory cycle. It appears that the nucleus may be involved in the elaboration of the neurosecretory material in the cells.
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  • 75
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    Notes: The blood circulation of the Stannius corpuscles, like that of the kidneys to which the corpuscles are attached, represents a portal system. The corpuscles receive blood from the dorsal caudal vein and from a vein coming from the hypaxial musculature. They are drained by veins which enter the caudal parts of the kidneys and therefore endocrine substances released by the corpuscles pass through the kidneys before they enter the general body circulation. The corpuscles are penetrated by sympathetic nerves coming from a small subvertebral ganglion. It is likely that these nerves innervate the muscular coat around the blood vessels. The muscular coat surrounding the renal blood vessels, the collecting tubules and part of the ureters, is innervated by nerves from the same ganglion. The secretory activity of the gland cells appears to be controlled by blood borne factors, because neither synaptic contacts with these cells, nor gap junctions among the cells, have been found in thin sections and freeze-etch replicas of the corpuscles.The corpuscles contain two cell types, both presumed to have endocrine function. Histochemical and ultrastructural data indicate that the gland cells produce glycoproteins. It is likely that the contents of the secretory granules are released by exocytosis. One cell type is structurally similar to the cells described in many other teleosts and thought to be engaged in the synthesis of a hypocalcemic hormone. The ultrastructure of the second cell type resembles cells described only in other migratory species: salmonids and eels. It may be involved in the control of monovalent ions.
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    Journal of Morphology 153 (1977), S. 107-117 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The glandular layer constitutes the greatest bulk of the human soft palate and is composed of individual compound tubulo-acinar salivary glands. Connective tissue partitions of the submucosa divide the glandular layer into lobules of irregular shapes and sizes. The glands are interwoven and bound firmly together by a connective tissue stroma rich in elastic fibers. The secretory units consist of elongated, branched, and sometimes convoluted tubules lined by a single layer of pyramidal mucous cells.Mucous secretion by acini is supplemented to some degree by mucous acinar cells, which were found as epithelial components of all ducts except the main excretory ducts, suggesting a diffuse distribution of progenitor cells. Some mucous acini communicate with highly convoluted intercalated ducts which occupy partially isolated positions within inter- and intralobular connective tissue septa. These ducts follow the connective tissue septa and eventually join the main duct system. The significance of this system of intercalated ducts is not known. A supplemental functional role is hypothesized.
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  • 77
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    Notes: Normal gill structure and thyroxine induced resorptive changes were studied in Ambystoma mexicanum. The gill is normally composed of a mesenchymal core covered with a multilayered epithelium. The general architecture is simpler than that of the teleost and elasmobranch, but the vascular arrangement is analogous. There are three basic cell types in the epithelium: a characteristic epithelial cell containing tonofibrils and mucus, a ciliated cell with an ultrastructure similar to that of the chloride cell, and the mucin-filled Leydig cell. The basal lamella and mesenchymal tissue appear typical of amphibians.Cytologic changes during thyroxine induced gill resorption varied with cell type. Some epithelial cells demonstrated a cytoplasmic response with swelling of mitochondria and rough endoplasmic reticulum and late, lytic nuclear changes, while others remained viable and went on to cornify. Ciliated cells showed early changes in nuclear chromatin pattern followed by rapid, progressive dilatation of endoplasmic reticulum. Leydig cells sustained variable changes leading to collapse of the perinuclear mucus, and cells of this type were absent in mature epidermis. Early basement membrane changes included widening and reduplication of the adepidermal membrane followed by morphologic fraying of collagen plies. There is no cytologic evidence to suggest that autolysis plays a major role in gill tissue dissolution.Resorption involved the maintenance of structural integrity in the face of diminishing physical dimensions. The epithelium became cornified, the basement lamellae dissolved, and the mesenchymal tissue was resorbed through action of macrophages in an orderly distal to proximal direction.
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    Journal of Morphology 154 (1977), S. 19-37 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Sea cucumbers, Stichopus moebii, have a unique specialization of their blood vascular system: The vascular follicle network is composed of numerous small chambers (follicles) interconnected by minute vessels. The fine structure of the follicle system was studied in detail. The follicles are composed of several layers: an external ciliated epithelium, neuromuscular layer and basement membrane, connective tissue, and a fenestrated endothelial lining. The follicle lumen is filled with coelomocytes and necrotic cells surrounding particles of iron. The follicle may function in coelomocyte production and destruction.
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  • 79
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    Notes: Timed-sequence studies have shown that reticulate scales on the ventral footpads of birds do not undergo “epidermal placode” formation during their morphogenesis, but arise as symmetrical evaluations similar to the scales of snakes and lizards. Unlike the scutellate scales on the dorsal surface of the foot, in which the formation of an “epidermal placode” and its subsequent morphogenesis result in distinct outer and inner epidermal surfaces, the reticulate scales elaborate only one type of epidermal surface.
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    Journal of Morphology 154 (1977), S. 115-131 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The arrangement and distribution of oxytalan fibers in Australian marsupials has not previously been reported. Periodontal tissues of wombat, wallaby, possum, and marsupial mouse were examined to ascertain oxytalan fibre organization. Despite adaptation of the marsupial masticatory apparatus to different diets the oxytalan fibre organization in the periodontal ligament shows a basic pattern which corresponds with that reported in other animals. The oxytalan system forms a continuous meshwork of fine, branching fibres which completely invests each tooth root and connects adjacent teeth. Thick ribbon-like apico-occlusally orientated oxytalan fibres, thought to form by the coalescence of thinner fibres, are restricted to the periodontal ligament. The oxytalan fibres are embedded in cementum and attached to blood vessels in the periodontal ligament. Oxytalan fibres do not insert into alveolar bone. Histological evidence indicates functional remodelling of the oxytalan fibre system in continuously erupting teeth.
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  • 81
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    Journal of Morphology 154 (1977), S. 157-186 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In Patella vulgata the 32-cell stage represents a pause in the mitotic activity prior to the differentiation of the mesentoblast mother cell 3D. At the onset of this stage, the embryo is radially symmetrical. Nevertheless, the plane of bilateral symmetry is indicated as it passes through the macromeres forming the vegetal cross-furrow. From the early beginning of the 32-cell stage, all four macromeres intrude far into the interior and touch the centrally radiating cells of the first quartet of micromeres. The two cross-furrow forming macromeres (3B and 3D) intrude the farthest and come into contact with the greatest number of micromeres. Finally, the contacts are extended significantly and maintained with only one of these macromeres. From that moment, this cell can be called the macromere 3D and the dorsoventral axis is determined. The evolution of the internal cell contacts between the micromeres of the first quartet and the macromeres indicates an essential role of the former in the determination of one of the latter as the mesentoblast mother cell, and thus in the determination of dorsoventral polarity.
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    Journal of Morphology 154 (1977), S. 459-477 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A process of nucleolar reorganization apparently identical to that encountered in intestinal epithelial cells (Adamstone and Taylor, '72) develops in kidney cells of aging rats. The polymorphic nucleoli of young tubule cells soon change to amphinucleoli and, while terminal nucleolar reorganization is delayed in cells of collecting tubules, in the nephrons nucleoli soon begin to undergo terminal reorganization becoming bipartite structures with separate plasmosomes and karyosomes. This suggests disruption of the DNA-dependent RNA protein transcription system and failure to maintain the flow of messenger RNA into the cytoplasm. Old cells are not discarded immediately from the kidney tubules and they retain much rough endoplasmic reticulum, numerous ribosomes and polysomes and large plasmosomes. Thus a high RNA concentration is known to develop in old kidney tissue while protein synthesis is also known to be low (Kanungo et al., '70; Buetow and Ghandi, '73). Nucleolar counts show gradual increase in bipartite nucleoli at the expense of amphinucleoli and in the senescent kidney bipartite nucleoli predominate. It is suggested that nucleolar reorganization, with final separation of plasmosomes and karyosomes, includes the process of nucleolar segregation and is triggered by some innate nucleolar mechanism in response to encoded genetic information stored in the nucleolus during nucleogenesis. At this time both DNA and RNA are incorporated into the developing nucleolus. It is also to be noted that two shifts in nucleolar dominance occur with advancing age. These may be fundamental to the process of aging and to the onset of senescence. Furthermore, the changes in dominant nucleolar types are the direct result of the process of nucleolar reorganization.
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  • 83
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    Journal of Morphology 223 (1995), S. 47-83 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The Notothenioidei, a perciform suborder of 120 species, dominates the ichthyofauna of the Southern Ocean around Antarctica. Unlike most teleost groups, notothenioids have undergone a corresponding ecological and phyletic diversification and therefore provide an excellent opportunity to study the divergence of the nervous system in an unusual environment. Our goal is to evaluate notothenioid brain variation in light of this diversification. To provide a baseline morphology, we examine the gross morphology and histology of the brain of Trematomus bernacchii, a generalized member of the family Nototheniidae. We then examine the variation in brain gross anatomy (32 species) and histology (10 species) of other notothenioids. Our sample represents about 27% of the species in this group and includes species from each of the six families, as well as species representing diverse ecologies. For comparison we reference the well-studied brains of two species of temperate perciformes (Perca flavescens and Lepomis humilis). Our results show that, in general, notothenioid brains are more similar to the brains of temperate perciforms than to the unusual brains of cave-dwelling and deep-sea fishes. Interspecific variation in gross brain morphology is comparable to that in Old World cyprinids and is illustrated for 17 species. Variation is especially noteworthy in the ecologically and geographically diverse family Nototheniidae. Measurements indicate that sensory regions (olfactory bulbs, eminentia granularis, and crista cerebellaris) exhibit the most pronounced variation in relative surface area. Association areas, including the corpus cerebelli and the telencephalon, exhibit moderate variation in size, shape, and lobation patterns. Regulatory areas of the brain, including the saccus vasculosus and the subependyma of the third ventricle, are also variable. These regions are best developed in species living in the subfreezing water close to the continent. In some species the expanded ependymal lining forms ventricular sacs, not previously described in any other vertebrate. Three species, including two nototheniids (Eleginops maclovinus and Pleuragramma antarcticum) and the only artedidraconid in our sample, have distinctive brains. The unique brain morphology of Pleuragramma is probably related to a sensory (lateral line) specialization for feeding. Within the Nototheniidae, a phyletic effect on cerebellar morphology is evident in the Coriiceps group and in the Pleuragramminae. Neither phyletic position nor ecological factors (water temperature, position in the water column, dietary habits) alone fully expalin the pattern of notothenioid brain diversification. © 1995 Wiley-Liss, Inc.
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    Journal of Morphology 223 (1995), S. I 
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    Journal of Morphology 223 (1995), S. 125-148 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The metamorphic species Eurycea bislineata is presented as a standard for evaluating the relationship between cranial ontogeny and life history in hemidactyliine plethodontid urodeles. Past and present descriptions are combined into a comprehensive summary of postembryonic skull development for this species, and the sequence, sizes of onset, and morphogenetic pathways are documented for all major remodelling events. Developmental series are also compared intraspecifically, between two populations of E. bislineata that differ in metamorphic size, and interspecifically, with species having different larval periods (Hemidactylium scutatum, Gyrinophilus porphyriticus, Pseudotriton ruber, E. wilderae, E. longicauda guttolineata) and with epigean (E. tynerensis, E. nana, and E. neotenes) and subterranean perennibranchiates (Haideotriton wallacei and Typhlomolge rathbuni). Cranial ontogeny is largely conserved in these hemidactyliines despite their disparate life histories. Outside the dichotomy of metamorphic and perennibranchiate development, variation is limited to interspecific differences involving the nasolacrimal duct, the repeated loss of the scleral cartilage, and minor dissociation of several metamorphic and postmetamorphic remodelling events. Some, but not all, of this variation is consistent with evolutionary differences in metamorphic size and age. The comparison of metamorphic and perennibranchiate hemidactyliines reveals a unique cranial ontogeny for urodeles, characterized by the abrupt and synchronous timing of almost all postembryonic remodelling, including the nasal skeleton, and the complete absence of these events in perennibranchiate forms. © 1995 Wiley-Liss, Inc.
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    Journal of Morphology 223 (1995), S. 175-190 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The ontogenesis and involution of thymus in cichlid fishes was studied with the aim of comparing development in the bottom-spawning species Tilapia zillii and T. tholloni, and in the mouth-brooding species Oreochromis auratus, O. niloticus, O. mossambicus, and Sarotherodon galilaeus. For comparison, data are also given on bottom-spawning Cichlasoma spp. from America and mouth-brooding Pseudotropheus auratus and Aulonocara nyassae from Africa. Developmental changes were followed histologically by means of light and electron microscopy of sections, beginning with embryos 24 h after fertilization, up to 14-year-old specimens of O. auratus. In all these fish, the anlagen of the thymus glands begins from the third and fourth gill pouches, and their development shows a high correlation with the pace of general organogenesis, which differs greatly in the bottom-spawning and mouth-brooding cichlids. In juveniles of bottom-spawners of 20-40 mm total length and in mouth-brooders of 40-60 mm total length, three cell types are present in the thymus: thymocytes, with large, dense nuclei; epitheliocytes, with long cell extensions containing bundles of tonofibrils; and reticulocytes, with short, granulated cell extensions. Hassall's corpuscles start to develop in larvae of T. zillii at 20-35 mm total length, and in specimens of 40 mm and more total length the corpuscles are typical, formed by inner and outer rings of epitheliocytes. At 30-45 mm total length, cell debris starts to accumulate in the interior of the corpuscles as an early sign of regression. As involution continues, macrophages accummulate within and around the Hassall's corpuscles. The epitheliocyte rings are eventually completely broken down. Isles of thymocytes persist in tilapias from the age of 1-14 years, but most of the thymus volume is occupied by blood lacunae and pigmented macrophage aggregations. The morphology is similar in the mouth-brooding species Pseudotropheus beginning at 1.5 years of age. © 1995 Wiley-Liss, Inc.
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  • 87
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    Journal of Morphology 223 (1995), S. 215-223 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The ventral sucker of Schistosoma mansoni cercaria is a cupshaped structure that is attached to the ventral surface of the organism by a homogeneous connective tissue that surrounds the acetabular glands. The sucker consists of an extensive complex of circular and longitudinal muscles. The longitudinal muscles extend outwoard in a radial pattern to form the cup of the organ. Intermingled with the muscles are nerve bundles and subtegumental cells (cytons). Dendritic nerve fibers connect to sensory papillae which are found on the surface tegument. Two types of sensory papillae are present: a commonly found unsheathed uniciliated papilla, and a previously unidentified tegumental encapsulated structure. Tegument with spines covers the ventral sucker, although the tegumental encapsulated sensory papilla lacks spines. © 1995 Wiley-Liss, Inc.
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  • 88
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    Journal of Morphology 223 (1995), S. I 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 89
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    Journal of Morphology 223 (1995), S. 225-242 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The neuronal connections of the tritocerebral commissures of Periplaneta americana were studied in the brain-suboesophageal ganglion complex and the stomatogastric nervous system by means of heavy metal iontophoresis through cut nerve ends followed by silver intensification. The tritocerebral commissure 1 (Tc1) contains mainly the processes of the subpharyngeal nerve (Spn) whose neurons are located in both tritocerebral lobes and in the frontal ganglion. Some neurons of the frontal ganglion project through the Tc1 to the contralateral tritocerebrum. A few fibers in this commissure were observed projecting to the protocerebrum and the suboesophageal ganglion. There are tritocerebral neurons which pass through the Tc1 or the tritocerebral commissure 2 (Tc2) and extend on into the stomatogastric nervous system. One axon of a descending gaint neuron appears in the Tc2. This neuron lies in the tritocerebrum and connects the brain to the contralateral side of the ventral nerve cord. In addition, sensory fibers of the labral nerve (Ln) traverse both commissures to the opposite tritocerebrum. The anatomical and physiological relevance of the identified neuronal pathways is discussed. © 1995 Wiley-Liss, Inc.
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  • 90
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    Journal of Morphology 223 (1995), S. 243-261 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This study examines the dosage dependency of thyroid hormone (TH)-mediated remodelling in the cranial skeleton of the hemidactyliine plethodontid urodele, Eurycea bislineata. One set of experiments quantifies morphogenetic responses in 21 tissues for four size-age classes of larvae immersed in four different T4 concentrations. A second set varies both the period and concentration of T4 treatment to evaluate the effect of different TH profiles on adult tissue shape. The tissues surveyed in this study exhibit a 100-fold range in TH sensitivity. Those in regressive morphogenesis have tissue-specific sensitivities which correlate with the timing of their remodelling in natural development: bone resorption is more sentitive than cartilage resorption and is initiated earlier in metamorphosis. In contrast, the TH sensitivities of tissues in progressive morphogenesis vary within each tissue type and even within some tissues, and they do not correlate with timing in natural development. Some explanation for this discrepancy is offered by the constant spatial and temporal relationships between nasal cartilage and dermal bone, which suggest that some TH-mediated ossification may additionally require induction by cartilage. Also, the failure of nasolacrimal duct morphogenesis at all but the lowest dosage correlates with the inductdion of integumentary changes that may preclude duct formation. Variable T4 treatments produce no effect upon the adult skull, other than loss of the nasolacrimal duct and/or foramen. These results have two developmental implicatons. First, the dosage dependencies of the nasolacrimal duct, ossification sequences, and cranial remodelling patterns all support a TH profile with exceptionally low levels at larval stages and at least a 100-fold increase at metamorphosis. Second, a small change in the rate of TH activity has the potential to effect a large-scale rearranggement and restructuring of TH-dependent remodelling. The lack of such transformations in metamorphic plethodontids suggests that TH activity is highly conserved in this group. © 1995 Wiley-Liss, Inc.
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  • 91
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    Journal of Morphology 224 (1995) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 92
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    Journal of Morphology 223 (1995), S. 303-323 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The sharply tapering skull of the honey possum is delicately constructed and has only a few, minute teeth; its mandible is reduced to a thin, flexible rod. The mandibular fossa has been diplaced caudally to the caudomedial corner of the squamosal. Head skeletons of the feathertail glider and western pygmy-possum, omnivores that are closely related to the honey possum, bear greater resemblance to the distantly related carnivorous fat-tailed dunnart than to the honey possum.Selected muscles associated with the jaws, hyoid, and tongue of these four mouse-sized (9-22 g) marsupials are described for the first time. The honey possum is characterized by a greatly reduced temporalis that is almost completely hidden by the eye. Its digastric consists of a single belly that inserts onto the caudal margin of the mylohyoid. The lateral pterygoid is relatively long as it extends caudally to insert onto the elongated mandible. The stylohyoid originates high up on the caudal surface of the tympanic bulla; it curves around the caudal and ventral surfaces of the bulla to reach the basihyoid. The insertion of the genioglossus is restricted to the caudal quarter of the tongue. Homologous muscles of the feathertail glider and western pygmy-possum are more similar to those of the fat-tailed dunnart. In addition to the very different musculoskeletal system, the honey possum has an unusual tongue that tapers to a fine point. © 1995 Wiley-Liss, Inc.
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  • 93
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    Journal of Morphology 223 (1995), S. 325-339 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Xenopus laevis interphotoreceptor matrix (IPM) contains a relatively aqueous insoluble wheat germ agglutinin (WGA)-binding component containing unidentifiied sialoglycoconjugates (Wood et al [1984] J. Comp. Neurol. 228:299-307). The appearance of WGA-binding macromolecules in the IPM was assessed during late embryonic stages (32-45) and in retinal rudiment cultures, using lectin cyutochemistry and Western blotting techniques. Metabolic labeling of the neural retina versus retinal pigment epithelium (RPE)-choroid of juvenile Xenopus with 35S-MET was also evaluated in vivo and in vitro. Lectin cytochemistry of eyes from developmental stages 32-42 demonstrated distinct WGA-ferritin-binding sites on the developing outer segment membranes and in the IPM compartment. At stages 44-46 extensive WGA-binding domains were present as an extracellular network with other randomly scattered domains near the retinal pigment epithelium. Retinal rudiments from stage 32-33 were isolated and allowed to differentiate in hanging drop culture (Hollyfield and Witkowsky [1974] J. Exp. Zool. 189:357-377) with or without an iinvesting pigment epithelium. Cultures developing with RPE exhibited an elaborate IPM with an anastomosing meshwork of WGA-ferritin binding sites. In the absence of RPE only limited amoutns of binding restricted to the immediate vicinity of the developing photoreceptor outer segement membranes was observed. When Western blots were probed with WGA-HRP, stage 32-45 retinas demonstrated a major WGA-binding band of 126 kD. Similar amounts of WGA-binding macromolecules were synthesized in preparations cultured in the presence or absence of the investing RPE. During development the major WGA-binding component is a 126-kD protein. Equivalent synthesis of this protein in the presence and absence of RPE suggests that the PE is not required for synthesis of this 126-kD component. These results suggest that the retina is the primary site of synthesis of the WGA-binding components of the Xenopus IPM, whereas the PE plays a principal role in their assembly and organization. © 1995 Wiley-Liss, Inc.
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  • 94
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    Journal of Morphology 224 (1995), S. 23-29 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The ovaries of Orthezia urticae and Newsteadia floccosa are paired and composed of numerous short ovarioles. Each ovariole consists of an anterior trophic chamber and a posterior vitellarium that contains one developing oocyte. The trophic chamber contains large nurse cells (trophocytes) and arrested oocytes. The total number of germ cells per ovariole (i.e., cluster) is variable, but it is always higher than 32 and less than 64. This suggests that five successive mitotic cycles of a cystoblast plus additional divisions of individual cells are responsible for the generation of the cluster. Cells of the trophic chamber maintain contact with the oocyte via a relatively broad nutritive cord. The trophic chamber and oocyte are surrounded by somatic cells that constitute the inner epithelial sheath around the former and the follicular epithelium around the latter. Anagenesis of hemipteran ovarioles is discussed in relation to the findings presented. © 1995 Wiley-Liss, Inc.
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  • 95
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    Journal of Morphology 224 (1995), S. 111-123 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The forelimbs of hylobatids (gibbons and siamang) are distinctive among tetrapods in that they are loaded in overall tension during normal locomotion. While hylobatid ulnae must also encounter bending stresses in the course of their full range of locomotor behavior, their loading regime differs from that of quadrupedal anthropoids in that these bending stresses are distributed evenly along the bone, are not exerted in a preferred plane, and are probably of generally lower magnitude. This study examines the degree to which hylobatid ulnae are adapted to this suspensory loading regime. We obtained cross-sections of ulnae at various increments along the length of the bone using CAT scans. The sample comprises 476 cross-sections representing the ulnae of 25 individuals from five species of comparable body size. We show that in gibbons and siamang, the patterning of ulnar cross-sectional area and resistance to bending in the dorsoventral plane along the ulnar diaphysis differ from that of similarly sized quadrupedal anthropoids in the manner predicted by a suspensory loading regime. We also find the same pattern for the ulnae of Ateles, whose loading regime may be fairly similar to that of hylobatids. However, we find that the cross-sectional shape of the ulnar diaphysis in hylobatids and Ateles does not differ from that of quadrupedal monkeys in the manner predicted by a suspensory loading regime. © 1995 Wiley-Liss, Inc.
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  • 96
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Topics: Biology , Medicine
    Notes: Luteal morphology of the American alligator is unique when compared to other reptiles but is similar to that of its phylogenetic relatives, the birds. The theca is extensively hypertrophied, but the granulosa never fills the cavity formed following the ovulation of the ovum. The formation of the corpus luteum (CL) is correlated with elevated plasma progesterone concentrations, which decline dramatically after oviposition with the onset of luteolysis. Unlike those of most other reptiles, the central luteal cell mass is composed of two cell types; one presumably is derived from the granulosa, whereas the other is from the theca interna. Both cell types are present throughout gravidity but only one cell type is seen during mid to late luteolysis. A significant decline in luteal volume occurs following oviposition and continues throughout the post-oviposition period. The fastest decline in luteal volume occurs in the month immediately after oviposition; this rate then slows. Luteolysis appears to continue for a year or more following oviposition, as distinct structures of luteal origin can still be identified in animals 9 months after oviposition. The size of persistent CL can be used to determine whether a given female oviposited during the previous nesting season. Females with CL having volumes greater than 0.2 cm2 or CL diameters greater than 0.4 cm were active the previous season. © 1995 Wiley-Liss, Inc.
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    Journal of Morphology 224 (1995), S. 125-129 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The myology of Rhinoderma darwinii is re-analyzed. Fourteen muscles (m. deltoides scapularis, m. coracoradialis, m. coracobrachialis brevis, m. omohyoideus, m. cucularis, m. interhyoideus, m. levator mandibular posterior externus, m. levator mandibular posterior articularis, m. levator posterior longus, m. geniohyoideus lateralis, m. geniohyoideus medialis, m. intermaxillaris, m. iliofibularis and m. iliofemoralis) are unique with respect to either structure or points of origin and/or insertion. An apical supplementary element of the m. intermandibularis is reported for the first time in the species, and another muscle, associated with the skin of the thigh, is described for the first time among anurans. Myological characters may be useful characters for future systematic and phylogenetic analysis of the Rhinodermatidae, one of the less diversified and enigmatic groups of neotropical frogs. © 1995 Wiley-Liss, Inc.
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  • 98
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Temperature-dependent sex determination (TSD), in which the temperature at which an egg incubates determines the sex of the individual, occurs in egg-laying reptiles of three separate orders. Previous studies have shown that the embryonic environment can have effects lasting beyond the period of sex determination. We investigated the relative roles of incubation temperature, exogenous estradiol, and gonadal sex (testis vs. ovary) in the differentiation of adult morphological and physiological traits of the leopard gecko, Eublepharis macularius. The results indicate that incubation temperature, steroid hormones, and gonads interact in the development of morphological and physiological characters with incubation temperature resulting in the greatest differences in adult phenotype. Incubation temperature did not affect reproductive success directly, but may influence offspring survival in natural situations through effects on adult female body size. Postnatal hormones seem to be more influential in the formation of adult phenotypes than prenatal hormones. These results demonstrate that TSD species can be used to investigate the effects of the physical environment on development in individuals without a predetermined genetic sex and thus provide further insight into the roles of gonadal sex and the embryonic environment in sexual differentiation. © 1995 Wiley-Liss, Inc.
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  • 99
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    Journal of Morphology 225 (1995), S. 345-355 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Developmental studies of the Recent Australian lungfish, Neoceratodus forsteri, show that this species has two sets of functional tooth-bearing bones in the lower jaw of young hatchlings. These coincide with an early stage in the life history when the fish is strictly carnivorous. In N. forsteri, a paired tooth-bearing dentary and an unpaired symphyseal bone and tooth develop slightly later than the permanent vomerine, prearticular, and pterygopalatine tooth plates, which appear at stage 44 of development, and erupt with the permanent dentition between stages 46 and 48, when the hatchling first starts to feed on small aquatic invertebrates. At these stages of development, all of the teeth are long, sharp, and conical and help to retain prey items in the mouth. Disappearance of the transient dentition coincides with complete eruption of the permanent tooth plates and precedes the change to an omnivorous diet. Existence of a transient marginal dentition in this species of lungfish suggests that the presence of an apparently similar marginal dentition in adults of many species of Palaeozoic dipnoans should be considered in phylogenetic analyses of genera within the group, and when analysing the relationships of dipnoans with other primitive animals. © 1995 Wiley-Liss, Inc.
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  • 100
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    Journal of Morphology 226 (1995), S. 1-24 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The intervertebral joint of the teleost, Perca flavescens, is formed by opposing amphicoelus centra whose rims are connected by external ligaments. The tissue, located within the space formed by these structures, is derived from the notochord and consists of the elastic externa, the fibrous sheath, and the notochordal cells. The cellular tissue within the joint has many characteristics of a stratified epithelium, and when examined with the transmission electron microscope, at least three morphologically distinct regions can be recognized. First, a peripheral single layer of columnar to squamous-shaped cells lies on a basement membrane immediately deep to the fibrous sheath. Second, several layers of cells, each containing a large central vacuole, occur. Third, in the deepest part of the joint, several layers of attenuated cells surround intracentral fluid-filled lacunae and form a transverse septum across the joint. All cells in this tissue are interconnected by numerous desmosomes. Further, an extensive intermediate filament network exists in all three types of cells. The intermediate filament network in the vacuolated cells is arranged cortically around a membrane-bound vacuole, and suggests that these cells may act as passive cellular hydrostats. The squamous cells surrounding the joint lacunae are structurally similar to mammalian epidermal cells, and the intermediate filament network within them is layered parallel to the surface of the lacunae. The organization of these cells suggests that they are the tensile component of extracellular hydrostats within the intercentral joint. These cellular and extracellular hydrostats within the intercentral joint would function to resist the compressive and tensile stresses encountered during undulatory swimming. © 1995 Wiley-Liss, Inc.
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