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  • LUNAR AND PLANETARY EXPLORATION  (1,394)
  • Life and Medical Sciences  (832)
  • ASTRONOMY  (492)
  • 1995-1999
  • 1980-1984  (1,400)
  • 1975-1979  (1,318)
  • 1980  (1,400)
  • 1976  (1,318)
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  • 1995-1999
  • 1980-1984  (1,400)
  • 1975-1979  (1,318)
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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 150 (1976), S. 19-58 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A thin, compressible, lateral suture and ventral plate overlap permit limited movement of the thick and rigid dorsal and ventral plates of Fuscouropoda agitans. Seven pairs of large dermal glands debouch onto the surface. Trochanteral rotation permits defensive leg adpresion and an insectan type of ambulation. The complex hypopharynx-pedipalpal-coxae has a buccal and cheliceral cavity separated by an atriculated epipharynx. The pharynx is Y-shaped in cross section. Extensive paired salivary glands lie above the very long and dexterous 3-segmented chelicerae, and a large pair of coxal glands debouch on coxae 1. From four blunt-ended tracheae, bundles of unbranching tracheoles extend in specific tracts to all organs. The ventriculus is small with three pairs of large caeca; a tightly packed single layer of digestive cells individually enlarged to absorb-phagocytize and digest the food. A typical mesostigmatid excretory tube is present. A typical acarine synganglion is present; mixed nerves have a basal swelling. A postulated neurosecretory organ arises from the pedipalpal nerve. The oocytes enlarge within funicular stalks from the walls of the small median ovary. A large spermatophore is stored in the seminal vesicle; fertilization occurs during oviposition. A tension hinge partially opens both male and female genital plates; closure effected by muscles acting on very long genital plate apodemes. Within sequentially produced spermatogonial cysts of the testes, meiosis is completely synchronous. A large, multilobed male accessory gland produces a large volume of seminal fluid; a mixture of at least four secretions. The origins and msertions of the body wall, genital organ, digestive tract, mouthpart and leg muscles are listed and illustrated. A comparison of anactinotrichid and actinotrichid mites indicates fundamental and consistent morphological differences in aspects of the cuticle, leg articulations, digestive system, excretory system, reproductive system and coxal glands.
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  • 2
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 150 (1976), S. 279-297 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: An investigation of the structure of the iridescent scales of the green hairstreak, Callophrys rubi, reveals an internal lattice which is probably cubic close-packed in form. We present a model which explains the formation of the lattice in terms of packing of spheres and surface tension forces and generalize these results to internal structures in other Lepidopteran scales.
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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
    Notes: There are 36 to 42 taste bristles on each half of the labellum of Drosophila melanogaster; most of them are two-pronged with a pouch between them. Some end bluntly with a pore at the tip.Each taste-bristle has two lumina: one is circular, the other crescent-like in cross section. In most bristles four dendrites of chemoreceptor neurons run along the circular lumen. In five to seven taste-bristles only two chemoreceptor neurons are found. A mechanoreceptor neuron sends a dendrite to the base of each taste-bristle.The dendrites are surrounded by four concentrically-arranged sheath cells. The inner cell secretes the cuticular sheath; cells II and III are presumably two trichogens, one secreting the bristle material around the circular lumen, the other around the crescent-like lumen. Cell IV, especially rich in bundles of microtubules, secretes the cuticle of the socket, and corresponds to the tormogen. The neurons have the typical structure found in insect sensilla. In many sensilla one neuron is less electron-dense than the others and may be the water-sensor.On the medial side of the labellum between the pseudotracheae are rows of taste pegs covered by folds. In each peg one chemoreceptor and one mechanoreceptor are found.The number of axons in each labial nerve agrees with the total number of dendrites in all taste organs of each lobe.
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  • 4
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 150 (1976) 
    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 150 (1976), S. 423-451 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Stichopus moebii, a sea cucumber, has a closed circulatory system which is unique in its degree of development for the phylum Echinodermata. The gross anatomy, histology and fine structure of the system were studied. Blood vessels consist of a coelomic surface of ciliated epithelium, a layer of muscle and nerve cells, followed by connective tissue and luminal lining of endothelium. Basically the blood vascular system consists of two major vessels running parallel to the gut: the dorsal vessel pumps colorless blood via the vessels within the walls of the intestine into the ventral vessel. There are two specialized areas of the circulation: (1) At the upper small intestine 120 to 150 muscular single-chambered hearts pump blood from the dorsal vessel into a series of intestinal plates. (2) At the lower region of the small intestine the vasculature is associated with the left respiratory tree. Blood passing from the dorsal pulmonary vessel can take two routes to the gut, it either passes through myriads of minute respiratory shunt vessels entangled with the respiratory tree or it passes through a unique follicle network consisting of tiny channels periodically dilated into chambers filled with iron deposits, necrotic cells and developing coelomocytes.
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  • 6
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 150 (1976), S. 639-679 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Anatomical components of afferent innervation in the rim of the octopus sucker are described. In the sensory epithelium under the smooth cuticle two associated ciliated receptor cell-types (presumably chemosensitive) occur in clusters. A third ciliated receptor cell-type under the toothed cuticle may be a mechanoreceptor. A non-ciliated receptor cell-type of unknown function, under the toothed cuticle, is characterized by a microvillus-lined apical canal containing dense granular material. The axons of the latter two receptors go directly into large nerve tracts which nm through the infundibular muscle and on to the ganglion of the sucker. The axons of the first cell-types terminate on interneurons either in the base of the epithelium or below the epithelium. All the interneurons of the basal region of the epithelium migrate centripetally and develop into encapsulated interneurons. Within the epithelium, fine fibers provide collateral contact among cluster receptors. Collateral interaction among basal and encapsulated interneurons occur in the infundibular plexus. The microanatomy of the rim of the sucker suggests that chemosensory cues are funneled into the interneurons where they are concentrated into integrated signals, while other sensory input is probably sent directly to the ganglia of the sucker and/or arm.
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  • 7
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 150 (1976), S. 727-761 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The pyloric region of Eosentomon and Acerentomon (Insecta, Protura) is described. In both species the posterior cells of the midgut carry short microvilli. Beneath the epithelial cells there is a muscular pyloric sphincter for closing the intestinal lumen. Behind the sphincter is a wide pyloric chamber lined by cells with very long microvilli which point anteriorly toward the midgut. These cells regulate the passage of the intestinal contents into the hindgut. Secretions from the Malpighian papillae are emitted into the gut at this level. In Eosentomon three regions (R1, R2 and R3) are visible in the Malpighian papillae, whereas in Acerentomon region R1 is lacking. The R1 region contains secretory cells with elaborate glycoprotein-containing granules. The R2 region is composed of cells somewhat resembling the secretory cells of Malpighian tubules of insects. Presumably R1 and R2 cells emit secretions into the central cavity of each papilla. Cells of R3 form a duct for the secretion. It is suggested that the R2 region represents a basic excretory region, common to Protura, whereas the R1 region, in Eosentomon, may be a specialized area performing supplementary excretory functions.
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  • 8
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 150 (1976), S. 785-803 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This manuscript describes in precise detail the ultrastructural alterations produced as a result of laser microirradiation of nucleoli and nucleoplasm of tissue culture cells. Because of the general difficulty of single cell recovery, flat embedding, and serial sectioning, very few studies have ever been conducted on microbeam irradiated cells; yet the use of the microbeam technique has become widespread in functional studies of the nucleus. The results presented here demonstrate two classes of lesion material: small spherical electron dense bodies 0.05-0.02 μm in diameter and a larger, more irregular electron dense material up to 1 μm in length. The occurrence of these different types of lesion materials is described in control irradiated nucleoli and nucleoplasm, irradiated nucleoli and nucleoplasm in quinacrine treated cells, irradiated nucleoli and nucleoplasm in actinomycin D treated cells, and irradiated nucleoli and nucleoplasm in combined actinomycin D and quinacrine treated cells. In all the cells in which actinomycin D was employed, nucleoli were selectively irradiated in either their granular or fibrillar zones. The results of the ultrastructural studies are discussed in light of earlier functional studies.
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  • 9
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 150 (1976), S. 843-859 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The general form and adaptation of the digastric muscle in carnivores are reviewed and discussed. The digastric muscle differs from the general plan in certain aquatic carnivores and felids. In the pertinent aquatic species the muscle is enlarged. The observations suggest that the enlargement is an adaptation for rapidly opening the jaws against the resistance of water. In felids, the insertion of the muscle is much farther forward than in most other carnivores. The observations suggest that the development of short jaws in felids necessitated a compensatory anterior relocation of the digastric insertion in order to preserve the ability to achieve a large gape.
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  • 10
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 150 (1976), S. 889-899 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Homolid crabs (Hypsophrys) from water deeper than 700 m in the Straits of Florida and Arabian Sea have smooth darkened oval spots contrasting with the surrounding roughened integument on inner and outer surfaces of each pincer at the base of the fixed finger. Cuticle is thinner over these spots than over surrounaing tissues. Beneath each spot is an organ composed of two markedly contrasting layers of tissue: (1) an outer, densely staining layer of tightly packed tubules, relatively straight and perpendicular to the overlying surface proximally but progressively convoluted and narrowed distally, finally ending blindly in association with the overlying thinned cuticle; (2) an inner layer of relatively large, eosinophilic, irregular cells with dark nuclei also trending at a right angle to the integument and bulging into the hemal sinus of the hand but separated from it by an epidermal lining. Droplets secreted from the inner layer apparently move into and along the tubules. Similar organs are known in no other crabs. The function is unknown but the structure suggests that they may be photophores.
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  • 11
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 150 (1976), S. 763-783 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The ultrastructure of a well studied insect chemosensory unit is presented in this report. Two separate lumina are present in this chemosensory unit, the trichogen and sensillar lumina. The fluid within the trichogen lumen exclusively bathes the dendritic terminals, and may be involved with the reception and/or modulation of environmental stimuli. Cytoplasmic extensions of the trichogen cell which line the trichogen lumen may be involved in the production of the cuticular sheath. The sensillar lumen is bordered by the tormogen and a sleeve cell, and is continuous with the unoccupied channel of the setal shaft. Functions for the various cellular components of the blowfly chemoreceptor sensillum are offered.
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  • 12
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This study indicates that eggs containing calcium carbonate crystals occur in at least 36 of the 65 known families of the land snails (class Gastropoda: order Stylommatophora). Eggs from 22 of these families were available for examination. The x-ray diffraction data, available for the first time for 21 of these families, shows that these egg shells are all made of calcite only, or of a combination of calcite with smaller amounts of aragonite. All of the snail (body) shells examined were made of aragonite only. This is the first ultrastructural investigation of these egg shells, and it indicates that the eggs exhibit enough structural diversity to allow identification of parental animals to genus, and often to species level solely on the basis of egg shell ultrastructure.All of the calcified eggs may be divided into two groups: (1) partly calcified, with discrete crystals of CaCo3 dispersed in the jelly layer, and (2) heavily calcified, with a hard, brittle egg shell made of fused crystals of CaCO3 much like an avian egg. Both types of calcified eggs occur in oviparous as well as in ovoviviparous snails. Because of the wide distribution of calcified eggs in the Stylommatophora, and because of the occurrence of heavily calcified eggs in ancient families such as Partulidae, Endodontidae, and Zonitidae, the calcified egg is viewed as a primitive land snail trait associated with terrestrial adaptation. The function of the calcified egg shell, in addition to mechanical support of egg contents, is to supply the developing embryo with enough calcium to form the embryonic shell by the time of hatching.
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  • 13
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 148 (1976), S. 23-31 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: When cervical segments 14 to 15 of the chicken spinal cord are cut transversely and studied by routine histological and histochemical methods, an onion-shaped region, filled with thread-like fibers, if seen to surround the ependymal cells of the central canal and to be bounded laterally by the neural elements of the spinal gray matter. This area is negative for succinic dehydrogenase, beta-hydroxybutyrate dehydrogenase and cholinesterase activity, but very strongly periodic acid-Schiff positive. Diastase controls show the positive material to be glycogen. Parasagittal sections through this cervical region and into the upper thoracic cord, show the glycogen-rich region to extend longitudinally throughout the region. Because of its location and histochemical characterization, which, He similar to that of the ventral portion of the glycogen body, the term brachial glycogen budy is proposed for this structure.
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  • 14
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 148 (1976), S. 1-21 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Anterior dorsal ventricular ridge (ADVR) is a major subcortical; telencephalic nucleus in snakes, Its structure was studied in Nissl, Golgi, and electron microscopic lrerarations in several species of snakes. Neurons in ADVR form a homogeneous population. They have large nuclei, scattered cisternae of rough endoplasmic reticulum in their cytoplasm, and bear dendrites from all portions of their somata. The dendrites have a moderate covering of pedunculated spines. Clusters of two to five cells with touching somata can be seen in Nissl, Golgi, and electron microscopic preparations. The area of apposition may contain a series of specialized junctions which resemble gap junctions. Three populations of axons can be identified in rapid Golgi preparations of snake ADVR. Type 1 axons course from the lateral forebrain bundle and bear small varicosities about 1 μ long. Type 2 axons arise from ADVR neurons and bear large varicosities about 5 μ. long. The origin of the very thin type 3 axons is not known; they bear small varicosities about 1 μ. long. The majority of axon terminals in ADVR are small (1 μ. to 2 μ long), contain round synaptic vesicles, and form asymmetric active zones. This type of axon terminates on dendritic spines and shafts and on somata. A small percentage of terminals are large, 5 μ in length, contain round synaptic vesicles, and form asymmetric active zones. This type of axon terminates only on dendritic spines. A small percentage of terminals are small, contain pleomorphic synaptic vesicles, and form symmetric active zones. This type of axon terminates on dendritic shafts and on somata.
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  • 15
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    Journal of Morphology 148 (1976), S. 33-63 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Tooth development and replacement in fetal and adult viviparous caecilians (Amphibia: Gymnophiona) are described and analyzed according to current theories of tooth succession. The fetal dentition differs from that of the adult in morphology, position, and function. Teeth are used by fetuses to scrape the oviducal epithelium, thus stimulating the secretion of a nutrient substance. Fetal dentitions vary in morphology and position in different species. The ontogeny of teeth of several species is described and the patterns of addition of loci and of replacement are analyzed, Loci are added both posteriorly along the jaw and between existing loci as the jaw grows prior to ossification; subsequently addition is restricted to the posterior part of the jaw. Tooth replacement is alternate. The several rows and patches of teeth are the result of retention of replacement series on the dentigerous elements. Tooth development and replacement in a series of juveniles and adults of different sizes in a single species are also considered. Post-fetal patterns of development and replacement are similar to those seen in larvae and adults of oviparous species. Variation in numbers of teeth and proportions of teeth at particular stages occurs ontogenetically and among individuals of the same size, though proportions occur in a similar pattern throughout the series. The general pattern of tooth replacement in fetuses and adults can be explained by either Edmund's Zahnreihen theory or by Osborn's Tooth Family theory, but replacement in fetal tooth patches and the fetal-adult dentitional transition are explained by neither.
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  • 16
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    Journal of Morphology 148 (1976) 
    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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  • 17
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    Journal of Morphology 148 (1976), S. 65-87 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In Brallchiobdella pentodonta Whitman meiosis begins in follicles containing 16 spermatogonia. In each follicle the spermatogonia are connected by cytoplasmic bridges to a central anuclear cytoplasmic mass or cytophorus. They develop synchronously. Synaptonemal complexes are present in the primary spermatocytes. Spermatids contain a large globoid paranuclear body consisting of an acrosomal granule and coiled tubules which evidently receive the contents of the acrosomal granule and are considered the acrosome carrier. The spermatids separate from the cytophorus only when differentiation is completed.The ripe spermatozoon is relatively long. It has anteriorly the coiled tubules, followed by the nucleus, the mitochondrial sphere and the distal centriole from which the flagellum originates, A coiled ribbon-like structure encloses the flagellum along its entire length while a manchette of microtubules surrounds all the other structures of the sperm.
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  • 18
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    Journal of Morphology 148 (1976), S. 89-135 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The muscles and bones of the pectoral fin of Serrasalmus nattereri, the piranha, resemble those of generalized, lower teleosts with specializations related to a body shape adapted for high-speed carnivory; the pectoral fins being highly mobile with strong ligaments to the rays. The presence of two occipital nerves appears primitive, while the emergence of the subclavian artery within the branchial cavity, as in Gasteropelecus sternicla, appears specialized. The muscles and bones of the latter fish, a fresh-water flying fish, are specialized for self-propelled, aerial flight in the fusion of the right and left girdles greatly expanded for insertions of complex appendicular (flight) muscles, and in the consolidation of the rays and radials into one functional unit moving vertically in flight though contraction of vertical, massive ventral flight muscles. The bony pectoral anatomy of Electrophorus electricus, the electric eel, is specialized in having a mobile joint between the primary girdle and the cleithrum, the former being suspended vertically from the cleithrum by ligaments. The proximal radials and rays are very numerous and vertically aligned. The cleithrum is shaped to accommodate the extensive sternohyoid and pharyngocleithral muscles. The sheet-like appendicular muscles extend beyond the special joint and control its movement. The deeper muscles do not cross this joint. The arterial system is specialized in lacking a deep brachial artery.
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  • 19
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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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  • 20
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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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  • 21
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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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  • 22
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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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  • 23
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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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    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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    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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  • 26
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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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  • 27
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    Journal of Morphology 164 (1980), S. 161-166 
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    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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    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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    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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    Journal of Morphology 164 (1980), S. 311-311 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    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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    Journal of Morphology 165 (1980), S. 13-29 
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    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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    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
    Source: Wiley InterScience Backfile Collection 1832-2000
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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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  • 36
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    Journal of Morphology 149 (1976), S. 1-31 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The cibarial food pumps of aquatic Heteroptera contain specialized epipharyngeal triturating devices. In the Naucoridae, striated bands and transverse plates triturate particles against the underlying hypopharynx. Anterior to them lie a pair of oblique folds which play an accessory role. The gross morphology of these devices is very similar in representatives of five genera of typical Naucoridae (Ambrysus, Pelocoris, Limnocoris, Cataractocoris, Cryphocricos) and differs from that of the atypical genus Aphelocheirus.The scanning electron microscope reveals additional differences between Aphelocheirus and the typical genera as well as variations, among the latter, which are not visible with the stereoscopic microscope. The oblique folds of the typical Naucoridae are well developed and contain processes for trapping particles; in three genera the region posterior to the folds is also modified. In Aphelocheirus only the latter region appears to trap particles, and the oblique folds are smooth and weakly developed. The striated bands of all genera bear ventral ridges arranged into transverse zones with precise patterns. The fourzoned bands of Aphelocheirus have a very different pattern than the two-zoned bands of the other genera. Among the latter, Cryphocricos has a simpler pattern of ridges than the other typical Naucoridae. The ventral surfaces of the transverse plates are highly modified in Aphelocheirus and less so in the other genera; those of Cryphocricos differ from those of the other Naucoridae.The fine structure of the cibarial epipharynx supports the views of some systematists that (1) Aphelocheirus should be placed in the monogeneric Family Aphelocheiridae rather than in the Naucoridae, (2) Cryphocricos represents a different subfamily than the other four typical Naucoridae, and (3) Cataractocoris belongs in the same subfamily as Ambrysus rather than with Cfyphocricos.
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    Journal of Morphology 149 (1976), S. 53-71 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Appearance of collagen fibrils in the cuticle was seen by electron microscopy to be preceded by fonnation of a finely filamentous matrix material. At first, the fine filaments of the matrix are unorganized. However, signs of orthogonal ordering soon appear in the most superficial portion of the cuticle, and subsequently appear more basally and closer to the underlying epidermis. Meanwhile, fibrils of different staining properties and identifiable as collagen begin to be deposited in the superficial portion of the cuticle, the same region which first showed organized fine filaments. Then, like the fine filaments before them, the collagen fibrils polymerize more basally. Collagen appears to polymerize on the preformed skeleton of fine filaments as though the fine filaments caused the collagen to assemble. Neither the polymerization nor ordering of collagen fibrils seems to require direct cellular intervention but occur first in that portion of the cuticle which is furthest away from the underlying epidermis. The fine filaments may be self ordering, extracellular macromolecules which in turn determine the polymerization of collagen fibrils.
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    Journal of Morphology 149 (1976) 
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  • 39
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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 149 (1976), S. 265-277 
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    Topics: Biology , Medicine
    Notes: Oogenesis of the fresh-water triclad Dugesia dorotocephala has been studied by electron microscopical methods, with particular regard to the genesis and composition of the so-called “Balbiani body.” Its origin is clearly recognizable in young oocytes where the few mitochondria present seem to gather at the level of the perinuclear ooplasm. Here they surround dense masses of finely granular, fibrillar material probably coming from the nucleus. During the previtelloge ic period, mitochondria rapidly increase in number while the dense masses progressively dissolve.In the vitellogenic oocytes the Balbiani body shows its final configuration: it appears as a large area (up to 15-20 pm in diameter) consisting of innumerable densely packed mitochondria, some smooth vesicles and free ribosomes. This aggregate of cytoplasmic organelles remains unmodified in the mature oocytes.The function of the “Balbiani body” of D. dorotocephala is as yet unclear; it can only be asserted that it is not correlated with yolk production in which the endoplasmic reticulum and the Golgi complex are involved.
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    Journal of Morphology 149 (1976), S. 421-435 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: Whole ovaries from 16-day fetal mice were cultured for 6 to 20 days and then transplanted to the kidneys of ovariectomized adult mice where they remained for one to four weeks. After three weeks in the host's kidneys, many follicles developed within the transplants and became vesiculated. Many of the oocytes within these follicles had formed the first metaphase spindle of meiosis and several had completed the first polar body. Host mice bearing transplants that contained vesiculated follicles showed uterine stimulation and keratinization of their vaginae. However, ovaries that had been in culture for more than ten days before transplantation showed a limited response to the gonadotropins and never matured sufficiently to stimulate the host's reproductive tract. No ovulations occurred in any of the transplants.
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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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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    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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    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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  • 47
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    Journal of Morphology 163 (1980) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 48
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    Journal of Morphology 163 (1980), S. 219-230 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    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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  • 49
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    Notes: The infracerebral gland of Nereis is made up of three types of cells. C1 cells are hypertrophied pericapsular elements, whereas C2 and C3 cells have the morphological and cytological features of neurosecretory neurons. C2 and C3 cells give rise to centripetal “proximal processes” which extend into the brain through the midventral pocket formed by delamination of the brain capsule. Their “distal processes” terminate within the gland or its immediate vicinity. “Centrifugal fibers” arise from nerve cells located within the brain and appear to synapse upon the proximal processes of C2 cells in the region of the midventral pocket and in the ventral region of the brain. The cytology of C2 and C3 cells suggests that they are the source of distinct peptide hormones.
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  • 50
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    Journal of Morphology 150 (1976), S. 321-326 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Exercise affects the growth of the dorsal longitudinal flight muscles in the tsetse fly. Examination of electron micrographs of flight muscles taken from flies subjected to enforced exercise, “ormal” exercise and no exercise reveals that both mitochondrial and myofibrillar fractions of the muscles are stimulated to grow at a faster rate by enforced exercise but that the mitochondria respond more rapidly.
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  • 51
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: Ultrastructure and shell formation in the testaceous ameba, Lesquereusia spiralis, were investigated with both scanning and transmission electron microscopy and X-ray microanalysis. The nucleus, surrounded by a fibrous lamina, contains multiple nucleoli. The cytoplasm, containing a well developed granular endoplasmic reticulum, also contains remnants of starch granules in stages of digestion. Spherical aggregates of ribosome-like particles may be seen. Golgi complexes seem to produce both a nonordered fibrous material and an electron dense vesicle. Only the latter appears to bleb off from the Golgi complex. X-ray microanalysis demonstration of silicon in Golgi vesicles and in some dense vesicles suggests that the fibrous component of the cisternae may take up and concentrate silica to form the electron-dense component of the vesicles. Membrane-bound siliceous crystals are often seen adjacent to the Golgi, suggesting either a Golgi origin or platelet formation in vesicles after release from the Golgi complex. Both electron-dense bodies and siliceous platelets are released from the cell by a process similar to apocrine secretion and may be seen outside the cell in route to the shell during shell morphogenesis. Shell development involves fusion of electron-dense bodies to form a matrix, positioning of siliceous platelets in this matrix parallel to the shell surface, and development of a system of matrix chambers. A particulate glycoconjugate is released to the shell surface upon rupture of the matrix chamber.
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  • 52
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    Journal of Morphology 150 (1976), S. 359-368 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Stereological analysis of the ultrastructural composition of the pulmonary alveolo-capillary region of mice living at sea level compared with that of the same species (Phyllotis darwini) genetically adapted to life at 4,660 m reveals a trend at high altitude towards a greater volume percentage of tissue components. On a weight-specific basis, non-circulating tissue occupies a significantly greater volume in high-altitude mice, but air space and capillary contents are not correspondingly greater. Since the arithmetic mean thickness of the tissue layers and of the air-blood barrier are the same in the two altitudinal groups, the average alveolus must have a smaller volume in the high-altitude mice.Epithelial, endothelial, and erythrocyte surface areas per gram body weight are significantly greater in the high-altitude mice.Nuclear counts indicate that the larger lungs of mice adapted to high altitude are due to larger Pneumocyte I and II and endothelial cells rather than to an increase in the number of these cells. Hematocrits measured within the pulmonary capillaries in the two altitudinal groups were equal.An heretofore unrecognized feature of possible adaptive value is the surface/volume ratio of erythrocytes, which is similar for erythrocytes in alveolar space of mice at low and high altitudes but within lung capillaries is 14.7% greater at high altitude.
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  • 53
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    Journal of Morphology 150 (1976), S. 299-305 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: The neck region of the mature spermatozoon of Discus rotundatus is described. No evidence for a centriole or centriolar derivative is obtained. Nine striated coarse fibres and the two central fibres of the axoneme extend into the base of the implantation fossa. The axonemal doublet system is disrupted in the neck region. There are two fibrous accessory structures located between the central doublet and the striated coarse fibres.
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  • 54
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    Journal of Morphology 150 (1976), S. 307-319 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Explants of 4.5-day-old chick embryonic neuroretinas with mesenchyme were exposed to Methotrexate (MTX) in medium 199 with embryo extract. Proliferative responses of the cultured neuroretinas were followed radioautographically by administration of 3H-thymidine to the cultures. The DNA synthetic, mitotic and pyknotic responses of the ventricular cells of the neuroretina were followed over a 16-hour period. The responses observed suggested that MTX caused a synchronization of the ventricular cells in the pre-mitotic phases with no direct inhibition of mitosis. Furthermore, prolonged exposure to MTX resulted in the accumulation of labeled pyknotic cells, indicating a decline in the regenerative capacity of the proliferative ventricular cells.
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  • 55
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    Journal of Morphology 150 (1976), S. 369-397 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Topics: Biology , Medicine
    Notes: Successive tracheal cuticles of the dorsal longitudinal trunks are studied with the electron microscope. Minor differences seen at the light microscope level are seen as major qualitative and quantitative ones at the ultrastructural level. The larval and pupal cuticles are secreted by similar epithelial cells; these possess large polytene chromosomes. Cell division and possibly cell replacement occur prior to adult cuticle secretion. The findings are discussed in terms of cell specificity, intra- and inter-cellular pattern formation. This simple epithelium, the individual cells of which are capable of producing different cuticles, is interesting since the system is also shown to be responsive to hormone application.
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  • 56
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    Journal of Morphology 150 (1976), S. 453-461 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Topics: Biology , Medicine
    Notes: Eggs of the common snapping turtle, Chelydra serpentina, were incubated at constant temperatures ranging from 20°C to 30°C, At hatching, the oviducts were absent or incomplete in males; the testes were differentiated. In females at hatching, the oviduct was intact hut in some cases the gonad retained bisexual characteristics. Three months after hatching, the ovary was differentiated and contained follicles. Eggs incubated at 20°C and at 30°C developed into females in 100% of the cases. At 26°C, 99% of the individuals were males; at 24°C, 100% were males. More males than females developed at incubation temperatures of 22°C and 28°C.
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  • 57
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    Notes: New blastozooids of Polyzoa vesiculiphora, the polysytelid ascidian are produced by pallial budding of three types depending on the method of “isolated bud” formation; stolonic, planktonic and intermediate types. Differences among each type of bud are attributed to behavior of test-vessels composing a part of the bud. Isolated buds produced by each type are essentially equal in terms of their internal structures and their subsequent fate, and develop independently of their parent zooids. New test-vessels originate directly from the epidermis of a “prefunctional zooid,” while the test-vessels derived from the parent zooid finally disintegrate. The new test-vessels extended with branching under the ventral side of a “functional zooid,” ascend to the lateral side of it and participate in bud formation. Budding regions exist in three dimensions on the lateral wall of the mantle of the functional zooid, especially the right posterior part. During the life cycle of one functional zooid, the stolonic type buds appear at early and/or aged stages. Appearances of the stolonic type buds in early stages tend to repress those of the planktonic types. The number of planktonic type buds formed on a functional zooid at the same time is many more than that of the stolonic type. Such budding features are discussed from the viewpoint of behavior of the test-vessel system.
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  • 58
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    Journal of Morphology 150 (1976) 
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  • 59
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    Journal of Morphology 163 (1980), S. 27-35 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: The presence of scolopophorous organs in aquatic Heteroptera has been reported in a number of species. This study presents a morphological investigation of these sensory structures of Lethocerus (Belostomatidae) as observed with the scanning electron microscope (SEM). Paired mesothoracic and metathoracic organs are present. Externally, each sensory structure consists of a raised sensory membrane. The distal-most portion consists of thickenings of this sensory membrane (sclerite). The receptor neurons of the mesothoracic organ are of two types - one discolopidial sensillum and 12 monoscolopidial sensilla. The former is attached to the internal wall and distal thickening of the sensory membrane, while the latter are dispersed throughout the interior and attached to the internal wall of the sensory membrane. The structure of the organs suggest that an effective stimulus could be a compression of the membrane. A discussion of possible functions (pressure reception and hearing) is included.
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  • 60
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    Notes: Scanning electron microscopy (SEM) of the surface tubercles of a specialized mechanoreceptor found within the head of Elaphe obsoleta lindheimeri indicates that the tubercle consists of a craterlike structure with a peg emerging from its center. After removal of the outer keratinized layers of the epidermis, the SEM discloses a replicate tubercle on the underlying alpha keratin layer. Over 6000 tubercles were found within a single snake. The mechanoreceptors were more densely concentrated on anterior scales, and their number appears to be species specific so that they are more concentrated in snakes with smaller heads than in those with larger ones.
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  • 61
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    Journal of Morphology 148 (1976), S. 137-159 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: The gross and microscopic anatomy of the venom producing parotoid glands of Bufo alvarius has been studied by light and electron microscopy. Histochemical reactions for the presence of venom constituents and of components in biochemical pathways in the synthesis and release of venom were performed. The gland is composed of numerous lobules. Each lobule is an individual unit with a lumen surrounded by a double cell layer. Microvilli of the outer layer interdigitate with microvilli of the inner layer. Cells of the outer layer resemble smooth muscle cells, are rich in adenosine triphosphatase and glucose6-phosphatase, and contain numerous pinocytotic vesicles, glycogen granules and various organelles, These organelles include “crystalloids” of what seem to be highly organized agranular reticulum. These outer layer cells probably function in some aspects of venom synthesis, active cellular transport and contraction in the discharge of the secretory product. The inner cell layer demonstrates a positive chromaffin reaction, contains steroid material, various organelles, some pinocytotic vesicles and glycogen granules, and appears devoid of a plasmalemma on its inner surface. This layer is probably involved in venom formation and release via an apocrine type of secretion.Bufo alvarius parotoid gland shows significant morphological and histochemical differences from that of B. marinus and more nearly resembles a typical steroid producing organ.
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  • 62
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    Journal of Morphology 148 (1976), S. 177-184 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Topics: Biology , Medicine
    Notes: Small local wounds on the surface of the mouse lung, produced by cauterization, healed by a typical reparative process involving c1 migration and increased cell division in alveolar and bronchial tissues. The local cell division response closely resembled the compensatory cell division response in the same organ which follows unilateral pnemnonectomy or unilateral collapse of the lung: initially there was an increase in the rate of DNA synthesis followed by an increased rate of entry into mitosis, both of these functions returning to normal levels within a few days. It is therefore suggested that both types of response are governed by a single regulatory mechanism. The results do not support the view that the rate of cell division is regulated by systemically-circulating mitotic control factors and it is proposed that changes in the cell division rate, both in the reparative and in the compensatory types of response, are determined by local alterations ill the concentration of regulatory metabolites.The magnitude of the cell division response was much greater in bronchial than in alveolar tissue. a result which is consistent with the view that new alveolar tissue may be produced by the proliferation and differentiation of bronchial cells.
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  • 63
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    Journal of Morphology 148 (1976), S. 161-176 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Larvae of the stolidobranch ascidian Metandrocarpa taylori molt a thin sheath upon settling, then metamorphose and radiate a larval complement of vascular ampullae upon the substrate. These ampullae thereafter regress, “rest” in a reduced condition for several weeks, and then regrow into the oozooids definitive array of vascular ampullae in accompaniment to the development of the oozooidal vascular nest of test-vessels. Pallial buds emerge some four months after the larva settles; the oozooid has by then grown to a length of at least 2 mm and its vascular nest is surrounded by at least 16 vascular ampullae. Oozooids bud one to five buds (mean, 2.6) in a rather short period of blastogenic vigor, then persist in the colony. Late buds are frequently aborted. Buds appear anywhere around the basal margin of the oozooid, but more often on the left than the right and more often posteriorly than anteriorly. As other studies have observed with blastozooids, this study notes an integration of budding and the disposition of the elements of the test-vessel system of oozooids. Buds emerge oriented tangentially to the parental basal margin at the bud-site, then often rotate to point their anterior ends away from the parent. No larvae metamorphosed into oozooids with situs inuersus uiscerurn, but in this study two oozooids extruded blastozooids showing this anomaly; these blastozooids budded reversed zooids in turn, so that entire clonal lines showed the anomaly.
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  • 64
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    Notes: Guinea pig soleus, medial gastrocnemius and vastus lateralis muscles were compared for spindle density and distribution, number of intrafusal fibers per spindle and histochemical appearance of the axial bundle. A total of 326 spindles was used in the comparisons. Spindle density was over four times greater in the soleus than in either the medial gastrocnemius or vastus lateralis. In the soleus the spindles were distributed at random, but in the other two muscles no spindles were found in those fascicles in which fast-twitch glycolytic extrafusal fibers predominated. The average number of intrafusal fibers per spindle varied by less than 5% between the three kinds of muscles. About 80% of all spindles located had four intrafusal fibers, two of the nuclear bag type and two of the nuclear chain type. The histochemical appearance of the axial bundle was the same in each kind of muscle. Based on intensities of the myofibrillar adenosine triphosphatase reaction product at polar regions nuclear bag fibers were separable into two histochemical groups; nuclear chain fibers were of only one histochemical type.
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  • 65
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    Journal of Morphology 148 (1976), S. 193-207 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Topics: Biology , Medicine
    Notes: To establish a morphological baseline for experimental studies of differentiation using the cement gland as a model, the following observations are added to those on record. The elongated cells of Xenopus laevis cement glands have an internal organization displaying five distinct zones differing in structure and specialized function. The apical zone contains packed secretion vesicles apparently belonging to two different types. The transit zone appears to be devoid of major biosynthetic activity and contains secretion vesicles migrating toward the surface. The zone of biosynthesis is typically organized in concentric regions. The very elongated nucleus lies in the next zone. Finally, the storage zone is characterized by lipid droplets and yolk platelets.Only quantitative differences are observed between cells of young and mature cement glands. Though all cells have the same general organization they may probably be divided into two subtypes according to the structure of their cytoplasm. The epithelial cells surrounding the gland differ according to their position along lateral or basal borders.
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  • 66
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    Journal of Morphology 148 (1976), S. 209-225 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The fine structure of the mature sperm of the holothurian, Cucumaria miniata, and the ophiuroid, Ophiopholis aculeata, is described with particular reference to their acrosomal and centriolar satellite complexes, and compared to the sperm of other echinoderms.In Cucumaria, the acrosome is in the form of a diffuse acrosomal vesicle. It is unusual in that it apparently lacks an acrosomal membrane. A membrane separating the acrosomal vesicle from the periacrosomal material may not be equivalent to a typical inner acrosomal membrane. In Ophiopholis, the acrosome is dense, with some internal substructure, and is enclosed by a complete acrosomal membrane. In both species, the acrosome is partially surrounded by an amorphous periacrosomal mass. There is a notable absence of a subacrosomal depression and associated structures as found in other echinoderm sperm.The centriolar satellite complex (CSC) is essentially identical in both species. A reconstruction of the CSC is presented. The CSC consists of nine satellites radiating angularly from the distal centriole, each bifurcating at a dense node before inserting on a marginal ring containing circumferential microtubules. The ring is probably a cytoskeletal element. Immediately below the satellites are nine Y-shaped connectives. connecting each of the axonemal alpha doublets to the flagellar membrane.
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  • 67
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    Journal of Morphology 164 (1980) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 68
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    Journal of Morphology 164 (1980), S. 265-285 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Topics: Biology , Medicine
    Notes: The interstitial nematode Theristus caudasaliens n. sp. normally locomotes by hopping on the left side of its tail tip, a mode of locomotion that is unique among nematodes. The animal uses its caudal glands and caudal musculature to perform the hops, attaching itself momentarily between hops with the glands and executing the hops by straightening and curling the posterior part of its body.The caudal gland apparatus can be seen by electron microscopy to consist of five gland cells of two different types. Three of these cells, termed viscid glands, are involved in adhesion of the animal to substrates and produce ovoid granules with a central dense band. The other two cells are characterized by smaller, lessdense granules and presumably function in releasing the animal from substrates. The ducts of both gland types extend to the tail tip where they terminate in a common crescent-shaped space. Their secretions are released to the outside through two pores on the left side of the tail tip. There is no spinneret valve in this nematode. The muscles of the tail and of the mid-body region are developed to the same extent.The caudal gland apparatus can be compared with the duo-gland adhesive organs of other interstitial animals, but its homology with either these organs or the caudal glands of other nematodes is uncertain. Theristus caudasaliens is described as a new species.
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  • 69
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    Notes: The ventral surface of the most proximal tarsomere of each mesothoracic leg of the female black fly, Simulium venustum Say, bears approximately 60 bifurcate sensilla. Externally, a sensillum appears as a hair set into an asymmetric socket and with the distal tip flattened into two flared lobes. A single pore opens into a short groove at the base of the lobes. The hair shaft is divided into two lumina, one of which contains the dendrites. Each sensillum is innervated by four neurons, the dendrites of which extend unbranched to the pore. Sensillum liquor bathes the dendritic tips and extends through the pore into the adjacent groove and across part of the lobes. A sieve-like structure exists in the pore region of many if not all sensilla. At least two sheath cells are associated with each sensillum.It is suggested that, although the bifurcate sensilla have the internal structure associated with known contact chemosensilla, they have secondarily acquired an olfactory function which is facilitated by the flattened lobes which increase the adsorptive surface area.Along each side of the bifurcate sensilla is a row of sturdy spines, each innervated by a neuron with a tubular body, a characteristic of cuticular mechanoreceptors. These spines are likely tactile sensilla.
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  • 70
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    Journal of Morphology 165 (1980), S. 41-54 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Histology and cytology of dermal scales of the gymnophionans Ichthyophis kohtaoensis and Hypogeophis rostratus reveal their structure and the nature of their mineralization.Dermal scales are small flat disks set in pockets in the transverse ridges of the skin. Each pocket contains several scales of various sizes. A ring of “hypomineralization” of varying diameter may occur on scales of a particular dermal pocket but bears no relation to the diameter of these scales.Three different layers form the scales and are seen on sections perpendicular to the surface. The cells of the basal layer lie deepest. Each of the two or three more superficial fibrous layers is composed of bundles of fibres that are oriented in parallel. The orientation varies among layers. The striation of the fiber scales has a periodicity comparable to that of the surrounding dermal fibers. Squamulae form a discontinuous layer on the scale surface and are the only mineralized part of the scale. The minerals are deposited both on the collagen fibers passing from the fibrous layers into the squamulae, and in the interfibrillar spaces. Spherical concretions, either isolated or coalescent, reaching up to 1 μm, are found on the surface of the squamulae.The dermal scales of Gymnophiona present some analogies with those of evolved bony fishes. Their characteristics could make them an original model for the study of mineralization.
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    Journal of Morphology 165 (1980), S. 67-83 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Using light and electron microscopy, three hemocyte types are described in the hemolymph of the crayfish. The coagulocyte comprises 65% of the total hemocyte number and contains medium-sized cytoplasmic granules, abundant dilated rough endoplasmic reticulum, and a highly developed Golgi complex. It rapidly undergoes cytolysis in vitro and participates in coagulation by releasing the contents of its granules to the hemolymph. The granulocyte comprises 31% of the total hemocyte number and is capable of phagocytosis. It contains large, irregularly shaped cytoplasmic granules, a moderately developed Golgi complex, and moderate amounts of non-dilated rough endoplasmic reticulum. During coagulation in vitro, the cell attaches and spreads onto the substratum; this is followed by a slow intracellular granule breakdown and cytolysis. The amebocyte comprises 4% of the total hemocyte number and it is also capable of phagocytosis. It possesses small cytoplasmic granules, many vacuoles, a moderately developed Golgi complex, and large amounts of smooth endoplasmic reticulum. It is distinguished from the other two cell types by being stable and motile in vitro.
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  • 72
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    Journal of Morphology 165 (1980), S. 85-116 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Lateral cortex is the most laterally placed of the four cortical areas in snakes. Earlier studies suggest that it is composed of several subdivisions but provide no information on their organization. This paper first investigates the structure of lateral cortex in boa constrictors (Constrictor constrictor), garter snakes (Thamnophis sirtalis), and banded water snakes (Natrix sipedon) using Nissl and Golgi preparations; and secondly examines the relation of main olfactory bulb projections to the subdivisions of lateral cortex using Fink-Heimer and electron microscopic preparations.Lateral cortex is divided on cytoarchitectonic grounds into two major parts called rostral and caudal lateral cortex. Each part is further divided into dorsal and ventral subdivisions so that lateral cortex has a total of four subdivisions: dorsal rostral lateral cortex (drL), ventral rostral lateral cortex (vrL), dorsal caudal lateral cortex (dcL) and ventral caudal lateral cortex (vcL). Systematic analyses of Golgi preparations indicate that the rostral and caudal parts each contain distinct populations of neurons. Rostral lateral cortex contains bowl cells whose dendrites arborize widely in the outer cortical layer (layer 1). The axons of some bowl cells can be traced medially into dorsal cortex, dorsomedial cortex and medial cortex. Caudal lateral cortex contains pyramidal cells whose somata occur in layers 2 and 3 and whose dendrites extend radially up to the pial surface. In addition, three populations of neurons occur in both rostral and caudal lateral cortex. Stellate cells occur in all three layers and have dendrites which arborize in all directions. Double pyramidal cells occur primarily in layer 2 and have dendrites which form two conical fields whose long axes are oriented radially. Horizontal cells occur in layer 3 and have dendrites oriented concentric with the ependyma. Fink-Heimer preparations of snakes which underwent lesions of the main olfactory bulb show that the primary olfactory projections to cortex are bilateral and restricted precisely to rostral lateral cortex. Electron microscopic degeneration experiments indicate that the olfactory bulb fibers end as terminals which have clear, spherical vesicles and asymmetric active zones. The majority are presynaptic to dendritic spines in outer layer 1.These studies establish that lateral cortex in snakes is heterogeneous and contains two major parts, each containing two subdivisions. The rostral and caudal parts have characteristic neuronal populations. Primary olfactory input is restricted to rostral lateral cortex and seems to terminate heavily on the distal dendrites of bowl cells. Axons of some of these cells leave lateral cortex, so that the rostral lateral cortex forms a direct route by which olfactory information reaches other cortical areas. The functional role of caudal lateral cortex is not clear.
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  • 73
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    Journal of Morphology 165 (1980), S. 157-165 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The caudal neurosecretory system of the molly, Poecilia sphenops (Poeciliidae) was studied by light and electron microscopy. In this species the cell bodies form a focal nuclear group in the caudal spinal cord. The neurosecretory cells are in contact with glial elements, axon terminals, and the lumen of the central canal. The axons of the neurosecretory cells form a definitive tract, which leaves the spinal cord proper to penetrate a well defined neurohemal organ, the urophysis. The urophysis contains an abundance of neurosecretory granules within the neurosecretory axonal processes. This study is the first ultrastructural study of the caudal neurosecretory system in this family of fishes, which has been used as a neuroendocrine model. This species acclimates easily to the laboratory aquarium and may be most suitable for further studies on the effects of changes in external salinity on the caudal neurosecretory system.
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  • 74
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    Journal of Morphology 165 (1980), S. 167-174 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The relationships between dimensions of book lung subunits were measured and analyzed as a function of body size in diverse spiders over a body mass range of 3.4 to 3,190 mg. Book lungs are the characteristic respiratory gas exchange organs in these arachnids. Actual gas exchange occurs across numerous air-filled cuticular plates, which invaginate hemolymph sinuses within the abdomens of these animals. Characteristic linear dimensions of these air-filled compartments reflecting diffusion paths scaled to the 0.2 power of body mass and showed only a fourfold increase over the size range in the sample. This deviation from isometric scaling in the direction obtained and its numerical similarity to scaling of alveolar dimensions to body size in vertebrates was interpreted as an adaptation to reduce diffusion distances between these compartments and vascular fluids. Conversely, lengths and widths of these plates scaled to the one-third power of body mass, isometric scaling, and increased between six-and eightfold over the size range. This result is consistent with the hypothesis that respiratory gas distribution within spider lungs is achieved by convective mixing as has been recently hypothesized.
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  • 75
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    Journal of Morphology 165 (1980), S. 223-223 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 76
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    Journal of Morphology 165 (1980), S. 261-284 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This study carried out on the posterior caeca of Orchestia in intermolt by means of light and electron microscopy shows that the diverticula of the midgut consist of two segments which are different from an anatomical point of view. The distal segment is in close relationship to the dorsal blood vessel, whereas the proximal segment, twice as long as the distal one, only touches the haemocoel. The cells of the distal segment are characterized by a brush border, some apical extrusions, a great number of ribosomes, rough endoplasmic reticulum, often associated with the mitochondria, the matrix of which is clear, high activity of the Golgi complexes, and a great development of extracellular channels. All these features indicate an activity in synthesizing proteins and transport. In the proximal segment, the cells are characterized by a striated border, reduced intercellular space, and especially by a great development of the smooth endoplasmic reticulum sometimes associated with mitochondria having a dense matrix. These diverse features indicate absorption ion and water transport. From an ultrastructural point of view, the posterior caeca of Orchestia cannot be considered homologous to the Malpighian tubules. Whereas during molting the posterior caeca of Orchestia are sites of calcium storage, during intermolt they are probably involved in the processes of water and mineral regulation and excretion.
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  • 77
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    Journal of Morphology 166 (1980), S. 1-25 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The paired spermathecae of Rhodnius are simple tubular out-pocketings of the common oviduct. Each consists of a short muscular proximal duct and the distal glandular region with a blind tapering end. The spermathecal wall has a cuticular intima, slender columnar epithelial cells and ensheathing longitudinal striated muscle, connective tissue, tracheoles, and nerves. Glandular epithelial cells possess an elaborate apical secretion-filled tubular inpocketing with an extensively folded plasma membrane. Laterally, cells interact by desmosomes, septate desmosomes, and extensive interdigitations. The cytoplasm is rich in longitudinally oriented microtubules associating with membrane densities along the invagination, lateral, and basal plasmalemmae. Apical concentration of mitochondria suggests their role in secretion or ion transport. The possible role of the spermathecae in maintaining the stored luminal sperm and its role in transmitting the mating stimulus is considered in light of the epithelial ultrastructure. The ultrastructure of the spermathecae of Rhodnius differs significantly from that of other insects.
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  • 78
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    Journal of Morphology 166 (1980), S. 65-80 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Anatomical studies were conducted to characterize the source, type, and distribution of parathyroid gland innervation in European starlings. Denervation experiments demonstrated that the parathyroid glands and adjacent carotid bodies are innervated by nerve fibers originating in the nodose ganglion of the vagus nerve. In the parathyroid parenchyma, these fibers terminate adjacent to chief cells or near vascular smooth muscle. Vagal fibers also form synapses with catecholamine-containing glomus cells of the carotid body. Blood that first perfuses the carotid body subsequently perfuses the parathyroid parenchyma. These observations suggest that vagal innervation may influence parathyroid function in starlings either through direct chief cell innervation or through alteration of vascular perfusion. A neurohemal relationship also may exist between the carotid body and parathyroids.
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  • 79
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    Notes: The fine structure of the dorsal bristle complex and pellicle of non-developing Euplotes eurystomus is described in detail by scanning and transmission electron microscopy. The bristle-pit unit is a highly differentiated complex of organelles. The bristle complex is composed of a pair of kinetosomes (basal bodies) joined by a connective. The anterior kinetosome bears the bristle cilium, which contains a polarized network of particles (“lasiosomes”). The posterior kinetosome bears a very short, knob-like “condylocilium,” and has an associated striated fiber. Accessory ribbons of microtubules are also associated with the kinetosome couplets. Parasomal sacs, a septum connecting the bristle cilium to the anterior wall of the pit, core granules of the kinetosomes, and large membranous ampules are described. The organization of the bristle complex bears many similarities to the somatic ciliature of other ciliates. The pellicle of Euplotes is composed of a continucus outer cell membrane subtended by membranous alveoli, which contain a “fibrous mat.” Two sheets of subpellicular microtubules (longitudinal and transverse) are located just beneath the alveoli. The “epiplasm” seen in some other ciliates is apparently absent in Euplotes. The texture of the cell surface is a pattern of folds or rugae composed of the outer cell membrane and the upper membrane of the alveolus. The pattern of rugae probably defines the “silverline-system” of light microscopy.
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  • 80
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    Notes: Hypotrichs are among the most complex ciliates in terms of morphology and development. To study the fine structure of cortical morphogenesis associated with cell division in Euplotes eurystomus, three different methods of observation were employed: light microscopy of protargol-stained specimens, scanning electron microscopy of cells prepared by critical point drying, and transmission electron microscopy of sectioned material. Observations on the stages of morphogenesis give much new information about cortical development, particularly about proliferation and aggregation of kinetosomes (basal bodies), ciliary outgrowth, the topography of morphogenesis, cirrus resorption, and growth of the pellicle. During the formation of new cirrus the process of kinetosome proliferation is atypical, i.e., groups of prokinetosomes are seen oriented at random and, in some cases, prokinetosomes apparently are formed at a distance from nearby young kinetosomes. That the new cirri develop in surface grooves, the grooves elongate into “tracks,” and (in some cases) grooves are partitioned into separate tracks suggests that the grooves play a role in the orderly migration of the new cirri on the cell surface. Conspicuous morphogcnctic changes in the cell surface involve local growth of the pellicle. The process of pellicle growth apparently involves two basic steps: (a) growth of the outer cell membrane to form “bare regions,” and (b) formation of alveoli in the bare regions. Alveolar sheets are formed by fusion of alveolus precursor particles. Cirrus resorption is sequential over several stages of development, and old cirri are resorbed as the new cirri impinge on them. As the old cirri regress, both in situ resorption and retraction of axonemes into the cytoplasm occur.
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  • 81
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    Journal of Morphology 149 (1976), S. 33-51 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: The mature annelid cuticle contains orthogonally oriented collagen in a matrix capped superficially by a dense epicuticle with external corpuscles. The underlying epidermis is a simple columnar epithelium with two major cell types, mucous-secreting cells which secrete through channels in the cuticle to the exterior of the worm, and “supportive” cells which presumably produce and increase the cuticle by secreting into it.The structures of supportive cells, previously interpreted as specialized for establishing interfibrillar collagen order, are revealed by glutaraldehyde fixation as common cellular components without the qualities deemed useful to align collagen. Cell processes which penetrate and sometimes pass completely through the cuticle are not stable, not in geometric order, and lack cilia-like structure. Cilia, unlike the ubiquitous cellular processes, are highly restricted to regions of the epidermis with specialized functions. Cellular control, or other control, of collagen fibrillogenesis remains unestablished.
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  • 82
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    Journal of Morphology 165 (1980), S. 205-222 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Voles and lemmings are the most successful group of graminivorous rodents, but the adaptations allowing them to enter this niche are not fully known. Dissections of the masticatory musculature of the 12 genera and subgenera of North American microtines show an increase in the potential anterior vector component and in the potential vertical vector component of these muscles relative to the molar tooth row. The result is a separation of the compressive and propulsive functions of the masticatory muscles during the power stroke of mastication. This has led to the formulation of a propalinal “swing” hypothesis which is supported by vector analyses of the musculature.
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  • 83
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    Journal of Morphology 165 (1980) 
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  • 84
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    Notes: The morphology of the bean-shaped accessory glands (BAGs) of males of Tenebrio molitor is described. All cells in the secretory epithelium are long and narrow (300-400 mμ × 5 mμ). The seven types of secretory cells are distinguished from one another by the morphology of their secretory granules. Granule substructure varies from simple spheres with homogeneous electrondense contents to complex forms with thickened exterior walls or with crystalline and membranous contents. Individual cell types were mapped by staining whole glands with Oil Red O, and the cell distributions were confirmed by wax histology and ultramicroscopy. The secretions of all seven cell types form a secretory plug composed of seven layers. During mating, the secretory plug from each BAG is forced into the ejaculatory duct by contractions of a sheath of circular muscle. The mirror image plugs from symmetrical BAGs fuse and are transformed into the wall of the spermatophore.
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  • 85
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    Journal of Morphology 166 (1980), S. 387-387 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 86
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    Journal of Morphology 149 (1976), S. 121-137 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: Early embryogenesis is described for the southern corn rootworm, Diabrotica undecimpunctata Howardi Barber, at 24 ± 1°C. During the first four hours following oviposition, the maturation divisions and syngamy are completed. Morphological changes in the second polar body accompany syngamy. Cleavage divisions and energid migration occur during the fourth to the tenth hour. The vitellophags, which appear during cleavage divisions, are distinguished from the blastema-bound nuclei by having smaller, more densely staining nuclei. After completion of a uniform blastoderm (11-14 hour), cell division ceases until the completion of the germ band and the formation of the embryonic membranes (22 hour). This species has a pattern of amnion formation that is different from most Coleoptera but is shared with a few other chrysomelids, some Isoptera, and some Odonata.
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  • 87
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    Journal of Morphology 149 (1976), S. 105-119 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Each ocellar nerve in the house cricket Acheta domesticus contains giant nerve fibers of 10-15 μ diameter, characterized in Golgi Cox preparations by a single row of short collaterals which runs along nearly the entire length of a fiber. Numerous long collaterals are given off by thin fibers in the ocellar nerve; medium-size fibers give off relatively few collaterals.The lateral ocellar tracts extend posteriorly through the dorsal protocerebrum, crossing the protocerebral bridge dorsally. The smaller median ocellar tract runs more ventrally through the pars intercerebralis; posterior to the bridge its fibers turn out toward the lateral nerves. Golgi and cobalt preparations reveal branching of giant and mediu_-size ocellar fibers posterior to the bridge at two levels, forming bilateral regions of ocellar neuropile. No ocellar processes appear to be given off to the corpora pedunculata, centra! body, nervi corporis cardiaci, antenna! lobes, or circumesophageal connectives; it is uncertain whether ocellar collaterals extend into the protocerebral bridge or optic lobes. Cell bodies of giant and medium-sized fibers are located in the pars intercerebralis.
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  • 88
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    Journal of Morphology 149 (1976), S. 73-103 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The general morphology of the gills is similar in larval (ammocoetes) and parasitic adult sea lampreys, Petromyzon marinus, despite different methods of ventilation necessitated by their feeding habits.The gill lamellae are supported by randomly-distributed pillar cells which enclose blood spaces and collagen columns. The distribution of these cells in lampreys is different from that of higher fishes and it may be inefficient for respiratory exchange. The presence of cytoplasmic microfilaments suggests that these cells have the ability to reduce the lamellar blood spaces through contraction. Marginal channels at the tips of the lamellae are lined only by endothelial cells.The thickness of the water-blood pathway in lampreys falls within the range described for higher fishes, with the most efficient gas exchange likely occurring at the lamellar tips where only a single layer of epithelial cells is present. The abrupt increase in height of the epithelium near the lamellar bases in adults, compared to the gradual transition in height along the lamellae in ammocoetes, is perhaps reflective of higher oxygen requirements during the parasitic stage. The consistent appearance of wide, lateral intercellular spaces within the respiratory epithelium of lampreys indicates possible involvement of these spaces in transport.Mucous secretion appears to be an important function of the superficial platelet cells in ammocoetes. “Mitochondria-rich” and “mitochondria-poor” superficial cells are observed in both ammocoetes and adults, with the mitochondria-rich cells more prevalent toward the lamellar bases. The possibility that at least some of these cells may be involved in absorption is discussed. Mitochondria-rich cells in the interlamellar region are morphologically different in ammocoetes and adults but all possess an abundance of smooth endoplasmic reticulum and hence resemble “chloride cells” of higher fishes. The similarity of these cells in the parasitic adult lamprey to chloride cells of marine fishes may reflect the potential of the adult lamprey to osmoregulate in salt water. A scarcity of these cells in ammocoetes and their resemblance to chloride cells in freshwater fishes may reflect the restriction of larval lampreys to a freshwater habitat.
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  • 89
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    Notes: Sexual dimorphism in the distribution of antennal sense organs is common among adults of the genus Periplaneta. In three out of the four strains of Periplaneta americana examined, adult males had more contact chemoreceptors than females. In the fourth strain of P. americana and in P. australasiae, P. brunnea, P. fuliginosa, and P. japonica, no statistically supportable sexual dimorphism of contact chemoreceptors was found. However, in all strains and species of Periplaneta examined, sexual dimorphism was found in the total number and/or density of olfactory sensilla. Male adults had nearly twice as many olfactory sensilla as female adults. These observations are consistent with the behavioral observation that males within the genus Periplaneta rely on the reception of an airborne pheromone for the initiation of courtship behavior. In P. americana, where sexual dimorphism was found in the contact chemoreceptors, contact stimuli release the full wing raising display and presentation in males during courtship.
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  • 90
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    Journal of Morphology 149 (1976), S. 183-197 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The main excretory ducts (MED's) from the submandibular gland of adult cats were examined by electron microscopy. The ducts consisted of a pseudostratified epithelial lining surrounded by abundant connective tissue and numerous, small, longitudinally-oriented blood vessels. The taller epithelial cells were closely coherent, without the luminal clefts between adjacent cells that are characteristic of rat MED's. In the cat, these cells lacked basal membrane specialization, but showed considerable lateral interdigitation. Some microvilli were present on the apical surface. In a'few rare cells, the luminal surface bore cilia of typical appearance. The smaller, pyramidal basal cells had irregular basal surfaces that gave rise to one or more long cytoplasmic processes. The basal surface of the pyramidal cells was studded with hemidesmosomes. The cytoplasm contained abundant tonofilaments, which sometimes aggregated in prominent perinuclear bundles. Occasional goblet cells were present in the duct wall.MED's perfused either in situ or in a perfusion chamber with Locke's solution also were studied. Even after perfusion of 160 minutes duration, the ultrastructure of the ductal epithelium showed remarkably few alterations. The MED model system thus remains stable long enough to carry out physiological experiments which may produce ultrastructural alterations.
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  • 91
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    Journal of Morphology 149 (1976), S. 199-221 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The byssus attachment plaque and the tissues responsible for its formation were studied in M. califomianus by light microscopy and by transmission and scanning electron microscopy. It was shown that the plaque consists of at least three phases which ultrastructurally resemble three secretions considered to be collagen, mucoid material and polyphenol. The mucoid and polyphenol appear to mix as a colloidal suspension in which the latter is the continuous phase and forms the definitive bonding surface. Plaque collagen represents an extension of thread material into the cementing substance.Stimulated secretion within the ducts and distal depression of the mussel's foot shows a continuum of increasing heterogeneity from the inner toward the outer regions. This reflects the distribution of exocrine cell apices wherein exocytosis of polyphenol granules predominate deeply, mucous granules superficially and collagen granules in between.It is proposed that the morphology of the plaque conforms to theoretical physical-chemical requirements for adhesion under water.
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  • 92
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    Journal of Morphology 149 (1976), S. 159-182 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In this paper the cranial arteries, cranial arterial foramina, and bony canals of the Cheloniidae, Chelydridae, Pelomedusidae, and Chelidae are described in detail. From skull studies and published material, the general cranial arterial patterns of all the turtle families can be inferred. Sea turtles, the Cheloniidae and Dermochelyidae, possess both a large stapedial artery and a large artery supplying the orbit, which is possibly similar to the primitive cranial arterial pattern for turtles. From a primitive pattern in which stapedial and palatine arteries supply the orbit, the Chelydridae and Testudinidae retained a large stapedial artery and reduced the palatine artery, while the Kinosternidae and Dermatemydidae developed a large palatine artery and reduced the stapedial artery. The Trionychidae and probably the Carettochelyidae evolved a complex arterial pattern in which the stapedial artery was reduced somewhat and the pseudopalatine artery was substituted for the palatine artery. Pleurodires in general retained a large stapedial artery and reduced or eliminated the palatine artery. The Podocneminae, including the Madagascar species, developed a highly modified carotid canal, which is found in no other turtle group. The facts which have been presented should aid in fossil skull studies and in understanding the evolutionary background of recent turtles.
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  • 93
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  • 94
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    Notes: Ethidium bromide (l0 μg/ml) and bromodeoxyuridine (25 μg/ml) were used to sensitize selective cell organelles to visible wavelengths of an argon ion Her (488 and 514 nanometers). Ethidium bromide was shown to be salabtlve In sensitizing nucleoli, chromosomes, and the centriolar region of PTK2 cells to the laser microbeam. Similarly, BrDU sensitized chromosomes to the microbeam irradiation. The lesions produced on the chromosomes when either agent was used appeared as a phase paling of the irradiated segment. Nucleolar lesions also appeared as a phase paling, and the centriolar region alteration appeared either as a phase paling or a phase darkening.
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  • 95
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    Journal of Morphology 150 (1976) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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  • 96
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 149 (1976), S. 547-565 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The labial gland of the adult sphingid moth, Manduca sexta, is composed of five distinct regions, each made of a single cellular type. Four of these regions are derivatives of the single specialized cellular population that makes up the caterpillar labial duct.Both the larval labial duct and its derivatives are large, polyploid cells with pleiomorphic nuclei. There is a definite cellular continuity between the larval and adult forms of these cells throughout metamorphosis; no mitoses or cell deaths are seen to occur in the gland during transformation.Cytological studies indicate that in the process of cell transformation the ducts first “dedifferentiate,” elongate, then redifferentiate. Intermediates in this process have well defined structures which should make this system useful in studying covert events in the transformation process.
    Additional Material: 1 Ill.
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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: Larval Typhlotriton spelaeus collected from five caves in Pulaski Co., Missouri, were kept as larvae or induced to transform in darkness or continuous fluorescent illumination. Larvae maintained in darkness for 215 and 279 days had smaller eyes, smaller rod inner and outer segments, and fewer metaphase figures in the genninative zone of the neural retina than comparable larvae maintained in light (258 lux). Except for visual cell size, differences were small and for each characteristic exceptions were observed. One larva kept in light showed early retinal degeneration comparable to that in transformed adults of T. spelaeus. All larvae exhibited optomotor behavior both before and after the experiment.Among animals induced to transform by L-thyroxin and maintained in darkness 111 to 366 days, visual cell and pigment epithelium degeneration was more extensive and more frequent than in animals kept for the same length of time in light (237-298 lux). In darkness the frequency of animals with retinal degeneration increased between 111 and 366 days. In light some animals exhibited pigment epithelium reduction with normal visual cells, and others had free, pigmented cells in the subretinal space. These effects were not comparable to degeneration in darkness. Eyelids covered the eyes of only a few animals in both light and dark treatments. The extent of eyelid encroachment over the eye was greater in darkness than in light. Most animals exhibited optomotor responses after experiments, but responses of animals kept in darkness were impaired in comparison to those of animals kept in light.
    Additional Material: 4 Ill.
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  • 98
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 150 (1976), S. 79-115 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The pectoral myology and osteology of the cyprinoids Notemigonus crysoleucas, the golden shiner, and Catostomus commersonnii, the common white sucker, resemble those of generalized, lower teleosts in structure and function, except in features related to the manipulation of the massive fifth ceratobranchial of cyprinoids by muscles attaching on the girdle. Catostomus is more specialized in having unique intercostal muscles to the girdle, complex subclavian arteries and lack of a superficial trapezius muscle. The bony pectoral anatomy of the siluriform, Ictalurus nebulosus, the brown bullhead, is highly specialized in relation to the presence and locking of the massive pectoral spine which is formed of fused dorsal and ventral propterygial rays; there is consolidation of the girdle through fusion of bones, presence of unique stabilizing bony structures, firm symphyseal union of bilateral girdles and the presence of friction-surfaces of girdle and spine for locking. The movements of the spine are specialized in the greater guidance offered by the girdle. Myological specializations are related mainly to ventral appendicular muscles which lock the spine. The nervous and arterial systems are generalized.
    Additional Material: 19 Ill.
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  • 99
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The inferior lobes of the shark hypothalamus were examined with light, transmission and scanning electron microscopy. The cells bordering the floor of the lateral recess appear to be typical liquor-contacting neurons. With scanning electron microscopy (SEM) the apical ends of these cells are seen to bulge into the ventricular lumen. In contrast, the roof is lined by a more typical ependymal cell characterized by numerous cilia and microvilli. In addition, SEM reveals several kinds of supraependymal cells with processes that appear to penetrate the ventricular lining. A periventricular nucleus underlies the ependymal cells. Neurons of the periventricular nucleus contain numerous lipofuchsin granules. The rest of the inferior lobe consists of many neuronal fibers. The morphology of the hypothalamic inferior lobe is discussed in relation to its possible role in feeding and aggressive behavior in both elasmobranchs and teleosts.
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  • 100
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 150 (1976), S. 711-725 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The fine structure of midgut cells in two species of Cladocera (Crustacea: Branchiopoda) has unique features when it is compared to that in the midguts of other arthropods. Features which suggest that food is absorbed in digested form are: the presence of the peritrophic membrane, the glycocalyx, the almost complete absence of pinocytotic vesicles, and the large surface area of a great number of microvilli. Digested products presumably pass into the hemolymph through the network of extracellular canals and cisterns surrounding the basal ends of intestinal epithelial cells. Cells of the midgut in Cladocera differ from those of other arthropods in the simplicity of their basal plasma membranes, which are not highly folded. The small number of membrane invaginations suggests that water reabsorption is very slight, as is the usual condition in aquatic animals.The origin and evolution of peculiar structures we call “multivesicular-like bodies” have been investigated. These display a variety of different morphological features. Some contain acid phosphatase activity and are considered as specialized lysosomes.
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