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  • Cell & Developmental Biology  (817)
  • Chemical Engineering  (814)
  • 1980-1984  (850)
  • 1975-1979  (653)
  • 1950-1954  (128)
  • 1980  (850)
  • 1977  (653)
  • 1953  (128)
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  • 1980-1984  (850)
  • 1975-1979  (653)
  • 1950-1954  (128)
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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 93 (1953), S. 1-17 
    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
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 93 (1953), S. 101-108 
    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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  • 3
    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
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 93 (1953) 
    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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  • 5
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 92 (1953), S. 545-577 
    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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  • 6
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 92 (1953), S. 579-595 
    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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  • 7
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 93 (1953), S. 19-43 
    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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  • 8
    Electronic Resource
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    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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  • 9
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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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  • 10
    Electronic Resource
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    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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  • 11
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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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  • 12
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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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  • 13
    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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  • 14
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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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  • 15
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    New York, NY : Wiley-Blackwell
    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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  • 16
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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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  • 17
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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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  • 18
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    New York, NY : Wiley-Blackwell
    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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  • 19
    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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  • 20
    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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  • 21
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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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  • 22
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    New York, NY : Wiley-Blackwell
    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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  • 23
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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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  • 24
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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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  • 25
    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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  • 26
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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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  • 27
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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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  • 28
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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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  • 29
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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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  • 30
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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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  • 31
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    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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  • 32
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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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  • 33
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    Journal of Morphology 154 (1977) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 34
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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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  • 35
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    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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  • 36
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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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  • 37
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    Journal of Morphology 154 (1977), S. 427-458 
    ISSN: 0362-2525
    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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  • 38
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    Journal of Morphology 163 (1980), S. 99-133 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Study of the visceral anatomy of 41 specimens of amphisbaenians representing 13 genera shows that they share a very distinct structure which differs from that found in either snakes or typical lizards. The left lung is large while the right is rudimentary or absent (unique); the kidneys are freely suspended in the coelom by a mesentery (unique); the spleen is usually embedded in the anterior end of the pancreas (as in snakes); the gall bladder lies in a notch in the liver, and the kidneys lie opposite each other (as in lizards). The distinctness of this pattern supports the recognition of the Amphisbaenia as a separate suborder of the Squamata.
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  • 39
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    Journal of Morphology 163 (1980), S. 175-190 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Light and electron microscope studies were made on harvestman oocytes during the course of their origin, differentiation, and vitellogenesis. The germ cells appear to originate from the ovarian epithelium. They subsequently migrate to the outer surface of the epithelium, where they remain attached often by means of stalk cells which suspend them in the hemocoel during oogenesis. The “Balbiani bodies,” “yolk nuclei,” or “nuage” constitute a prominent feature of young, previtellogenic oocytes, and take the form of large, but variable sizes of electron-dense cytoplasmic aggregates with small fibrogranular components. The cytoplasmic aggregates fragment and disperse, and cannot be detected in vitellogenic oocytes. The young oocytes become surrounded by a vitelline envelope that appears to represent a secretory product of the oocyte. The previtellogenic oocytes are impermeable to horseradish peroxidase under both in vivo and in vitro conditions. In addition to mitochondria, dictyosomes, and abundant ribosomes, the ooplasm of the previtellogenic oocyte acquires both vesicular and lamellar forms of the rough-surfaced endoplasmic reticulum. In many areas, a dense homogeneous product appears within the cisternae of the endoplasmic reticulum and represents nascent yolk protein synthesized by the oocyte during early stages of vitellogenesis. Later in vitellogenesis, the oocyte becomes permeable to horseradish peroxidase under both in vivo and in vitro conditions. This change is associated with a massive process of micropinocytosis which is reflected in the presence of large numbers of vesicles of variable form and structure in the cortical ooplasm. Both spherical and tubular vesicles are present, as are coated and uncoated vesicles. Stages in the fusion of the vesicles with each other and with developing yolk platelets are illustrated. In the harvester oocytes, vitellogenesis is a process that involves both autosynthetic and heterosynthetic mechanisms.
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  • 40
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    Journal of Morphology 164 (1980), S. 25-38 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The clitellar epithelium of the freshwater oligochaete, Tubifex hattai, is composed of four types of gland cells (Type I, II, III, and IV), in addition to the cells generally found in the epidermis of this worm. The possible function of these gland cells in cocoon formation was studied with the electron microscope.Type I cells discharge their secretory granules by means of compound exocytosis and provide the materials for the future cocoon membrane. Immediately after completion of the discharge from Type I cells, Type II and III cells simultaneously discharge their secretory granules by means of compound exocytosis. The secretions from Type II cells constitute a colloid in the cocoon lumen and probably cause structural modifications in the future cocoon membrane. The secretory products from Type III cells form the cocoon plug. Although the process of discharge of secretory granules from Type IV cells was not observed, the contribution of these cells to the cocoon formation, producing hoops on the outer surface of the future cocoon membrane and fixing its anterior ends on the clitellum, is inferred from a morphological comparison of the hoop and the structure of the secretory granules.
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  • 41
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    Journal of Morphology 164 (1980), S. 69-81 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The distribution and activity patterns of monoamine oxidase and monoaminergic (formaldehyde-induced) fluorescence in the central nervous system of web-building and hunting spiders have been studied using histochemical methods. Enzyme activity occurred in the neuronal perikarya and in varying intensity in the structures of the neuropile mass, but only when dopamine, adrenaline, and noradrenaline were used as substrates. The optic centres of the spider brain normally exhibited relatively strong enzyme reactions when compared with the staining intensity of the rest of the nervous system.The neuronal cell bodies contained numerous granules of yellow-green fluorescence. Monoaminergic fluorescence of the neuropile was generally a weak green. The optic mases of the hunting spiders, the anterior bridge, several commissures of the ventral cord, and the neural lamellae showed a slightly higher fluorescence intensity and single fluorescing granules.The results obtained indicate the presence of catecholamines in the spider nervous system.
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  • 42
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    Journal of Morphology 164 (1980), S. 107-119 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The tongue of the striped dolphin, Stenella coeruleoalba, shows a V-shaped row of pits on its posterior dorsum. Their development is described on the basis of macroscopic and light microscopic observations on fetal, young, and adult stages. Four to eight pits occur, most often five in the adult. Anlagen of the pits first protrude as round epithelial thickenings which later increase in diameter and become thin. The circular primordia then sink, and grooves oriented both circularly and radially develop in the walls of the shallow pits thus formed. Pits and grooves deepen with development so that older pits become lined with conical projections. As pits grow further, they become elongated anterolaterally, retaining slit-like openings. Each pit in the adult is 2-8 mm long and about 1 mm wide. The pits are not derived from lingual gland ducts but develop independently. Taste buds resembling those of other mammalian tongues can be found in young dolphins but are few in number and limited to the thin epithelium of the pit projections and to that of the side wall of the pits. They first appear in the late prenatal period but degenerate in the adult. A rich nerve supply is observable in the lamina propria below taste buds in the calf. The pits and their projections in the dolphin correspond to the vallate papillae of other mammals, but whether each projection or a whole pit corresponds to a single vallate papilla is undecided.
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  • 43
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    Journal of Morphology 164 (1980), S. 139-159 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Two morphologically distinct structures occur on the surfaces of the oral papillae in several loricariid catfish species; namely, (1) typical vertebrate taste buds composed of receptor and sustentacular cells and (2) brushlike projections, termed epidermal brushes, that represent specialized epidermal cells containing keratin. Both of these structures were studied with the combined use of light microscopy and scanning and transmission electron microscopy. The general body surface, fins, and rostral cutaneous processes of some loricariid catfishes are covered with taste or terminal buds but lack the epidermal brushes. It is suggested that the epidermal brushes found on the oral papillae serve as protective devices for the taste buds and as abrasive surfaces for substrate scraping during feeding. The taste buds on the oral papillae may detect any gustatory stimuli from the resulting substrate disturbance. Comparative studies reveal many differences in the number and spatial arrangement of these two structures on the oral papillae among the several species of the Loricariidae examined. These differences may represent functional adaptations to the various modes of life in the Loricariidae.
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  • 44
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    Journal of Morphology 164 (1980), S. 83-88 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The Y-organ has been histologically identified in all six larval stages of the crab, Cancer anthonyi. The paired glands are located anterior to the branchial chamber and ventral to the base of the antennules. In the first zoeal stage the gland consists of a cord of 6 to 10 epidermal cells with dark staining nuclei, sparse cytoplasm, and indistinct cell boundaries. As development progresses the glands become more complex through extensive folding and intertwining of the cellular cords. The glands in all larval stages show cyclical activity which corresponds to the molt cycle. Immediately following a molt the gland is dense and compact with little cytoplasm. At approximately day four in the molt cycle, the glands become greatly hyperthropied due to an increase in the number and size of the cytoplasmic vacuoles. These histological changes suggests a cyclical production and presumably the release of some product most likely ecdysone.
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  • 45
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    Journal of Morphology 164 (1980), S. 89-105 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The digestive tract of a harpacticoid copepod, Tigriopus californicus (Baker), was studied by using techniques of light and electron microscopy. Four cell types could be distinguished: type 1, an embryonic cell which will replace cells worn away or lost during secretion; type 2, a cell which synthesizes and secretes proteins and also plays a role in lipid absorption; and types 3 and 4, two cell types which absorb lipids. From the abundance of each cell type, the length of microvilli, the development of basal plasma membrane (PM), and luminal projections, the following conclusions were made. (1) The midgut caecum absorbs digested nutrients. (2) The anterior midgut absorbs nutrients and more importantly functions in merocrine and exocrine secretion. The presence of concretions in cell types 2 and 3 in the anterior midgut suggests that these tissues contribute in excretion, and in water and/or ion regulation. (3) The posterior midgut absorbs nutrients and contributes some holocrine secretion.
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  • 46
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    Journal of Morphology 164 (1980), S. 161-166 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Tactile hairs are present on all three subsegments of the antennal flagellum of the human louse. There is, in addition, a single chemoreceptor (tuft organ) on subsegment 2 and 12 or 13 chemoreceptors (one tuft organ, two pore organs and nine or ten pegs) on subsegment 3. The cuticle surrounding the bases of the pegs at the tip of the antenna is unusual in that parts of it are perforated by many fine pores. This cuticle is underlain by a thin layer of dendrites. This region may also have a chemoreceptor function.
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  • 47
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    Journal of Morphology 164 (1980), S. 121-138 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The heart-body of the marine worm Amphitrite, located within the supraesophageal dorsal vessel, is in the form of a cylinder the thin wall of which is deeply corrugated by luminal projections and folds along its entire length. It is anchored in places to the luminal surface of the dorsal vessel by an extracellular matrix containing collagen fibers. The luminal surfaces of both the heart-body and the dorsal vessel are covered by a basement membrane-like vascular lamina which in turn supports a discontinuous pseudoendothelium of littoral hemocytes.The cells of the heart-body constitute a pseudostratified, high columnar epithelium. They possess extensive rough endoplasmic reticulum (RER), a well developed Golgi zone, ferritin particles and granules, and several types of membrane-bound inclusions. Hemoglobin molecules identical to those in the circulation lie within cytoplasmic, membrane-bound vesicles. Analysis of our electron micrographs suggests the following sequence of hemoglobin production and secretion: Large quantities of a moderately dense flocculent material, probably globin, are synthesized in RER and move to the Golgi zone within partly rough- and partly smooth-surfaced transitional cisternae; small transport vesicles, formed from Golgi cisternae that have fused with transitional cisternae, convey the flocculent material from the convex to the concave face of the Golgi complex; a similar flocculent material and an amorphous, highly dense material are processed in the Golgi complex and are transferred to condensing vacuoles in which clearly identifiable hemoglobin molecules are first observed. Mature secretory vesicles containing only hemoglobin migrate to the cell periphery and discharge their contents by exocytosis. Hemoglobin molecules then cross the vascular lamina to reach the circulation.
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  • 48
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    Journal of Morphology 164 (1980), S. 167-211 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The dermopteran basicranium combines a primitively constructed and oriented auditory bulla formed by ectotympanic, rostral entotympanic, and tubal cartilage with derived features of the middle ear transformer and internal carotid circulation. Living dermopterans possess a primitive eutherian auditory region that has been structurally modified to perceive a lower frequency sound spectrum than probably was utilized by ancestral Mesozoic therians. Perception of the low to midfrequency range is enhanced in Dermoptera by reducing stiffness in the mechanical transformer while maintaining low mass of the component parts. Stiffness has been reduced by (1) development of an epitympanic sinus about four times the volume of the middle ear cavity proper, (2) detachment of the anterior process of the malleus from the ectotympanic, and (3) by delicate suspension of the ear ossicles within the middle ear.We apply to dermopterans a measure of hearing efficiency derived from recent functional studies of the mammalian middle ear that regards the middle ear mechanism as an impedance matching transformer. Calculation of the impedance transformer ratio for Dermoptera suggests that these mammals are relatively efficient in comparison to other eutherians in their ability to match the impedance of cochlear fluids to that of air at the eardrum. Dermopterans theoretically are capable of using over 90% of incident sound energy striking the eardrum at the resonant or natural frequency. Mechanical impedance of the middle ear transformer exerts a minimal influence on hearing efficiency due to low mass, little stiffness, and little frictional resistance.Analysis of measurements of the middle ear transformer published by Gerald Fleischer and integration of these data with current theory on the peripheral hearing mechanism in mammals allow us to propose a model that describes the structural and functional evolution of the mammalian middle ear transformer. Structural changes appear to be correlated with alteration in function from primitive small mammals with stiff middle ear transformers and high frequency dominated hearing to mammals with a wider range in body size with more mobile middle ear transformers and a greater range of frequency perception, often including improved sensitivity to lower frequencies.Mammals employ different anatomical strategies in attainment of increased hearing efficiency and sensitivity. Efficiency is improved by adjustment of lever and areal ratios of the middle ear transformer to achieve an optimum impedance match of external air and cochlear fluids. Sensitivity over a broad frequency spectrum is attained by minimizing mass, stiffness, and frictional resistance of the transformer. The morphology of the auditory region of both living and fossil mammals seems explicable in terms of selection pressure directed toward these ends.
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  • 49
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    Journal of Morphology 164 (1980), S. 311-311 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 50
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Analysis based on telemetered electromyography from the quadriceps femoris of Lemur fulvus, a Malagasy prosimian, during walking, galloping, leaping, and a variety of postural behaviors partially confirms and partially contradicts earlier hypothesized functions of this musculoskeletal complex. As predicted on the basis of morphological criteria (large physiological cross-section and long parallel fibers), the vastus lateralis is of special functional significance in leaping. This relatively large muscle consistently initiates the leap and frequently undergoes a very long period of force enhancement via active stretch. By contrast, the vastus intermedius fails to exhibit increased electrical activity and undergoes little or no active stretch during jumps. The myological details of vastus intermedius (short fibers, no fusion with other components), therefore, cannot be accounted for as adaptations to leaping. Rather, a primary postural role is indicated for the vastus intermedius, because in normal resting postures, with the knee quite flexed, it alone is continuously active. The existence of a fibrocartilaginous superior patella in the tendon of vastus intermedius, however, is most plausibly related to the complex tensile and compressive stresses generated in the tendon during the completely hyperflexed phase of leaping.The phasic patterning of the quadriceps femoris of Lemur fulvus does not point to any special role of the vastus lateralis or vastus intermedius during walking and galloping; it does indicate very different patterns of muscle recruitment in comparison to those in nonprimate mammals and some anthropoid primates. The forward cross walk (diagonal sequence, diagonal couplets) of primates versus the backward cross gait (lateral sequence) of most other mammals probably accounts for some of these differences. Lemur fulvus lacks the degree of elastic storage and release of kinetic energy in the quadriceps femoris that characterizes the gallop of dogs, cats, and Erythrocebus patas.
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  • 51
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    Journal of Morphology 165 (1980), S. 13-29 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The active motility of the cells of the yolk sac of the living Fundulus embryo was studied by time-lapse cinemicrography with phase contrast optics. In the teleost, the yolk sac lies peripheral to the body of the embryo proper and consists of a fluid-filled space bounded above by a superficial epithelium, the enveloping layer (EVL), and below by the yolk syncytial layer (YSL). The cell types treated in the present study are the enveloping layer epithelial cell, the stellate cell which lies in a layer flattened on the inner surface of the EVL, the epithelioid deep cell, the yolk sac amoebocyte, the yolk sac endothelial cell and the yolk sac melanoblast. The most actively motile cells examined in the present study are the yolk sac amebocyte and the melanoblast, which emigrates from the embryo proper at stages 19-21. The amoebocytes are compact rounded cells that move very rapidly by the extension of lamellipods with scalloped margins. The amoebocytes wander over the yolk sac in an apparently undirected fashion and invade the embryo proper when they happen to encounter it, moving between cells of the lateral mesoderm. The melanoblasts migrate by the gradual extension of elongated branching processes. Cells are sometimes monopodial, with movement being parallel to the long axis of the cell. Alternatively, movement may be perpendicular to the predominant long axis, with processes being extended alternatively from opposite ends of the cell obliquely forward, so the path described is a zig-zag to either side of the overall direction of movement. Although the melanoblasts show irregularity in their movement, the predominant direction of initial movement is away from the embryo proper. The major yolk sac blood vessels form in situ by the collective activities of presumptive endothelial cells that enclose volumes of the yolk sac space with sheet-like processes from the cell body and from the extensions that connect cells into networks.
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    Journal of Morphology 165 (1980) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 53
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    Journal of Morphology 165 (1980), S. 117-130 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Morphometric analysis of vertebral structure in caecilians (Amphibia: Gymnophiona) is presented. Ontogenetic variation in Dermophis mexicanus is analyzed through the 100+ vertebrae composing the column. Vertebral structure in adult D. mexicanus is compared with that in Ichthyophis glutinosus and Typhlonectes compressicauda. Centra of the atlas, second, tenth, 20th, and 50th vertebrae grow at allometrically different rates in D. mexicanus, though the 20th and 50th are not significantly different, Growth appears significantly slower in several dimensions of anterior and posterior vertebrae relative to midtrunk vertebrae in all three species. Mensural patterns throughout the entire column are similar in the terrestrial burrowers D. mexicanus and I. glutinosus; patterns in the aquatic T. compressicauda differ substantially from those of the burrowing species and are strongly influenced by allometry. Of the 112 D. mexicanus examined, 13.4% had vertebral anomalies, usually fusions.
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    Journal of Morphology 165 (1980), S. 131-155 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: Statoblasts of five higher phylactolaemates were compared morphologically. As a result, they were divided into two groups: Group I comprising Lophopus crystallinus, Lophopodella carteri, and Pectinatella gelatinosa, and Group II comprising Pectinatella magnifica and Cristatella mucedo. These two groups are thought to represent independent evolutionary series. In Group I and in P. magnifica, the statoblasts are curved to varying degrees after the manner of a saddle. When the dorsal and ventral valves are flattened, therefore, the contour is different between the two. In Group I, the outermost layer of a mature statoblast is hard-gelatinous and basophilic; it remains intact after the statoblast is set free. The statoblast does not float until it is dry, and the float is similar in size on both valves. In Group II, a mature statoblast is covered by a softgelatinous basophilic layer, which decays after the statoblast is released. The statoblast floats without drying, and the float is better developed on the dorsal valve than on the ventral. Moreover, in the members of Group II, large yolk granules are first formed, followed by much smaller yolk granules. When their statoblasts are treated with KOH, the shell is separated completely into two valves. These characters are common to many lower phylactolaemates. By contrast, in L. carteri and P. gelatinosa, the yolk granules are uniformly small and the capsule proper resists KOH treatment. On these points, L. crystallinus is somewhat different from these two species, suggesting its primitive nature.
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    Journal of Morphology 166 (1980), S. 203-216 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Teeth of fetuses of a caecilian, Dermophis mexicanus (Amphibia: Gymnophiona), show ontogenetic variation in crown structure from small, multidenticulate, and non-pedicellate to larger, spoon-shaped, pedicellate teeth with a single apical spike. Number of denticles decreases as enamel-secreting cells mature. Numbers of teeth and of tooth rows increase ontogenetically. A fetal vomeropalatine set of teeth is present in D. mexicanus but absent in species previously examined. Teeth transitional to the adult shape and arrangement appear shortly before birth. The transition is correlated with birth, not fetal size. There is relatively little increase in numbers of teeth during the juvenile period. The pattern of development does not fully agree with either morphogenetic field theory or with clone theory, both as defined by Osborn ('78). Sequence of initiation is appropriate to either. Tooth shape changes agree with aspects of clone theory. Multiple rows of fetal teeth and the transition to adult follow field theory. Clone theory holds that patterns of development and shape are self-regulated, field theory that they are controlled extrinsically. I suggest that substances regulating differentiation mediate early development, and hormones later development, including inception of adult teeth, and are comparable to “field substances” influencing primordia that originate according to clone theory. Components of both theories are appropriate to analyzing tooth development phenomena.
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    Journal of Morphology 166 (1980) 
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    Journal of Morphology 163 (1980), S. 9-12 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Previously unreported structures found on the head and thorax of several species of microcaddisflies (Trichoptera: Hydroptilidae) are described. Depending on the species, these presumptive pheromone-producing glands are found either (1) on the basal segment of the antenna, (2) on movable and immovable occipital sclerites, (3) as eversible organs from the occipital area of the head, or (4) on structures which are attached near the bases of the front wings.
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    Journal of Morphology 163 (1980), S. 37-44 
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    Notes: The morphology and organization of chromatophores in the neotropical glass-frog, Centrolenella fleischmanni (family Centrolenidae), were studied with both light and electron microscopes. Four types of pigment cells are described in the dorsal skin. The fine structure of two chromatophores corresponds to the typical amphibian xanthophore and iridophore; one is similar to the unusual melanophore found in phyllomedusine hylids; the fourth cell type is unlike any chromatophore previously described. Pigment granules in the unusual chromatophore are moderately electron-dense and have an irregular shape, suggesting a fluid composition. This pigment appears to be laid down in organelles similar in appearance to pterinosomes. The organization of pigment cells in this species differs from that of other green, leaf-sitting frogs in that there are few discrete groups resembling “dermal chromatophore units.” It is suggested that the unusual new pigment cell contributes significantly to the overall green color of C. fleischmanni.
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    Journal of Morphology 163 (1980) 
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    Journal of Morphology 163 (1980), S. 157-165 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Topics: Biology , Medicine
    Notes: Electron microscopy of the cerebral ganglionic commissure of the leech Macrobdella decora (Say, 1824) revealed numerous neurosecretory axons terminating in the neural lamella of both the inner and outer capsules, and in the neural lamella deep within the neuropile. The proximal protions of the terminals, with an investment of glial tissue, contain either numerous large homogeneously electron dense granules, or numerous large granules of varying electron density. The distal portions, often devoid of glia, display numerous infoldings, omega profiles, and electron dense focal sites, and contain numerous neurosecretory granules, small lucent vesicles, and, occasionally, acanthosomes. Statistical analysis of the size distribution and morphology of the neurosecretory granules showed that in many individual terminals the granules are not significantly different from those seen within four groups of neurosecretory cells found in the cerebral ganglion. These terminals, because of their diffuse nature, probably represent a neurohemal complex of a primitive nature. The term “intralamellar complexes” is proposed to describe the form and location of these neurosecretory terminals.
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    Journal of Morphology 163 (1980) 
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    Journal of Morphology 163 (1980), S. 219-230 
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    Notes: Rat submandibular gland was dissociated by enzymatic digestion with collagenase and hyaluronidase, followed by mild mechanical shearing and filtration through a nylon mesh. The dissociated cell populations contained predominantly groups of acinar cells which maintained their acinar arrangement. The morphological and functional viability of the cells was confirmed by electron microscopic examination and a normal secretory response to β-adrenergic or cholinergic stimulation was observed. Both isoproterenol (IPR) and carbachol caused the fusion of secretory granules into large vacuoles which were also continuous with the lumen, and into which the secretory product was released. Secretion was assessed quantitatively from the incorporation of 14C-glucosamine into the acinar cells and its subsequent release into the culture medium as labelled glycoprotein. IPR stimulated secretion to 125% of untreated controls in the concentration range 5 × 10-5 to 5 × 10-7 M, and to 110% of controls at 5 × 10-8 M, after 40 min incubation. Carbachol stimulated secretion to 131% of controls at 5 × 10-5 M and to 115% at 5 × 10-6 M but had no effect at 5 × 10-7 or 5 × 10-8 M. The secretory response was blocked by the respective β-adrenergic and cholinergic antagonists, propranolol and atropine. These findings show that dissociated rat submandibular acinar cells provide a useful in vitro model for the study of mucus synthesis and secretion.
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    Journal of Morphology 92 (1953), S. 207-239 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Journal of Morphology 92 (1953), S. 303-335 
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    Journal of Morphology 93 (1953), S. 465-487 
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    Journal of Morphology 93 (1953), S. 573-587 
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    Journal of Morphology 92 (1953), S. 39-77 
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    Journal of Morphology 92 (1953), S. 157-205 
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    Journal of Morphology 92 (1953), S. 273-302 
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    Journal of Morphology 92 (1953), S. 401-453 
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    Journal of Morphology 92 (1953), S. 513-529 
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    Journal of Morphology 93 (1953), S. 69-99 
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    Journal of Morphology 93 (1953), S. 177-283 
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    Journal of Morphology 93 (1953), S. 447-464 
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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 
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    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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    Journal of Morphology 152 (1977), S. 21-53 
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    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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    Journal of Morphology 152 (1977), S. 1-19 
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    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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    Journal of Morphology 152 (1977), S. 89-99 
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    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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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 88
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    Journal of Morphology 152 (1977), S. 101-140 
    ISSN: 0362-2525
    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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  • 89
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    Journal of Morphology 152 (1977), S. 153-169 
    ISSN: 0362-2525
    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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  • 90
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    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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  • 91
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    Journal of Morphology 152 (1977), S. 281-302 
    ISSN: 0362-2525
    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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  • 92
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    Journal of Morphology 153 (1977), S. 163-185 
    ISSN: 0362-2525
    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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  • 93
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    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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  • 94
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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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  • 95
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    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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  • 96
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    Journal of Morphology 154 (1977), S. 19-37 
    ISSN: 0362-2525
    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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  • 97
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    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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  • 98
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    Journal of Morphology 154 (1977), S. 115-131 
    ISSN: 0362-2525
    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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  • 99
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    Journal of Morphology 154 (1977), S. 157-186 
    ISSN: 0362-2525
    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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  • 100
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    Journal of Morphology 154 (1977), S. 459-477 
    ISSN: 0362-2525
    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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