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  • Life and Medical Sciences
  • 1980-1984
  • 1970-1974  (25)
  • 1940-1944
  • 1974  (25)
  • 1
    ISSN: 0045-205X
    Keywords: Life and Medical Sciences
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0045-205X
    Keywords: Life and Medical Sciences
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
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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: An arbitrary classification scheme is presented for the thirteen distinct types of secretory cells distinguished within the central nervous system of Dermacentor variabilis by several specific and general neurosecretory staining techniques. Comparisons to classic arthropod neurosecretory cell types are made and the histochemical implications of the chromophilic response of various secretory products are discussed. Dermacentor cells of Types I, VII, IX and X may be considered neurosecretory on the basis of intracellular elaboration and discharge of secretory product. Type II, III, IV, V, VI, XI and XII cells are considered as putative neurosecretory cells although secretory products were detected only within the perikarya. The large Type XII cells are also similar to motor neurones reported from other arachnids. Cells of Types VIII and XIII appear to be glial elements. The secretory products of Type XIIIA are distributed within trabecular processes in the subperineurium. These products may play a trophic role or they may have some endocrine function as a form of “gliosecretion”.
    Additional Material: 2 Tab.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 143 (1974), S. 385-395 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This paper examines the effect of early thymectomy on the subsequent development of lymphoid tissues in the toad, Xenopus laevis. At the time of thymic removal (8 days post-fertilization) all the lymphoid organ anlagen are at a rudimentary state of differentiation and contain few, if any, small lymphocytes. Despite the absence of any thymic tissue all thymectomized animals grew normally.Thymectomized larvae developed relatively normal lymphoid organs. However, lymphoid depletion was apparent in the splenic red pulp and in the pharyngeal ventral cavity bodies. Examination of the lymphoid organs of post-metamorphic Xenopus revealed reduction in spleen size following thymectomy. Lymphoid depletion was evident in the splenic red pulp of many thymectomized toadlets and reduction in proportion of white to red pulp was also noted in a few of these animals. Absence of the thymus had no apparent effect on the histology of the other lymphoid organs examined.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 144 (1974), S. 485-497 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: As part of program of research into insect cellular immunity, an integrated light and electron microscopic study of the hemocytes of seven members of the Order Dictyoptera has been made. In fresh hemolymph, five cell types, the prohemocytes, plasmatocytes, granular cells, spherule cells and cystocytes, are easilv distinguished. However, in thick Araldite sections and in thin sections in the electron microscope it is sometimes difficult to identify the various cell types. The reasons for this difficulty are discussed.Granules with a microtubular substrcture are found in the plasmatocytes, spherule cells and cystocytes. In the plasmatocytes these granules have a different ultrastructure than those in the spherule cells and cystocytes. The in vitro fragility of these granules in both the spherule cells and cystocytes during coagulation partially explains the previous confusion in distinguishing these two cell types.Evidence is presented which indicates that the plasmatocytes, granular cells and spherule cells represent a developmental series originating from the prohemocytes. Where exactly the cystocytes are derived from is unknown.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 142 (1974), S. 153-163 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Abdominal extra-adrenal chromaffin tissue, or paraganglia, was examined at the ultrastructural level to elucidate the innervation of this adrenal medullary homologue. Paraganglia display unmyelinated nerve fibers surrounded by Schwann cell cytoplasm. These nerves are separated from the paraganglion Type I (granule-containing) cells by cytoplasmic projections of paraganglion Type II (satellite) cells. However, serial sections show that the nerves eventually make synaptic contact with the Type I cell. At the axon-chromaffin cell junction, only the outer aspect of the nerve is covered by the satellite cell. The presynaptic endings contain numerous synaptic vesicles, mitochondria and glycogen particles. The vesicles are predominantly of the clear-cored variety, but a few possess centers which are elecron opaque. The pre- and postsynaptic membranes are separated bya subsynaptic space and occasionally exhibit the membranal densities usually associated with synaptic areas. These ultrastructural studies establish definite evidence that abdominal paraganglion cells are innervated.
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  • 7
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The synganglion of Dermacentor variabilis Say is a single nerve mass, condensed around the esophagus and within the periganglionic sinus of the ciculatory system. Protocerebral, cheliceral (including stomodeal bridge), and pedipalpal ganglia lie in the pre-esophageal portion of the nerve mass and bear optic, cheliceral, and pedipalpal nerves respectively. The unpaired stomodeal and the recurrent nerve which forms the hyper-esophageal ganglion arise from the stomodeal bridge. Paired primary and accessory nerves to the retrocerebral organ complex have mixed protocerebral-cheliceral origins. Pedal ganglia (including ventral olfactory lobes of pedal ganglia I) and composite opisthosomal ganglion lie in the post-esophageal nerve mass and bear pedal nerve trunks and two pairs of opisthosomal nerves respectively.Internally, the synganglion consists of cellular rind and fibrous core. A welldefined neurilemma with a laminar matrix covers nerve mass and peripheral nerves. The rind contains the somata of ganglionic neurons and ensheathing glial cells and is restricted to the synganglion mass. It is limited by two specialized glial layers, the external perineurium and internal subperineurium. Discrete glomerular formations are present within the protocerebrum and olfactory lobes. Olfactory glomeruli located in pedal ganglia I are associated with a pair of globuli cell groups.Possible physiological relationships between anatomical specializations of the synganglion, extraneural sinuses and circulating hemocytes are considered. The evolutionary significances of condensation in the stomatogastric neuropile regions and throughout the synganglion, together with the simplification and loss of glomerular formations, are discussed.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 144 (1974), S. 407-419 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The hermit crab, Pagurus pollicarus, has the same organization in its fourth abdominal ganglion as its macruran relatives in spite of the reduction in abdominal muscles, sensory receptors, and appendages. Connective axons are grouped into discrete bundles between which five groups of commissural fibers run to connect left and right sides. The neurites of ventral cell bodies run dorsally in characteristic groups between the connective bundles. The hermit crab fourth ganglion has two thirds as many cells as the crayfish and is laterally compressed. This reduction appears related to the reduction in the sizes of the ganglionic roots. The ventral fine fibered neuropil is larger on the left than the right side reflecting the loss of pleopods on the right side. The basic organization of decapod abdominal ganglia appears to permit considerable integrative flexibility within a relatively conservative morphological framework.
    Additional Material: 10 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 143 (1974), S. 259-283 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The male genital systems of two mysids, Archaeomysis grebnitzkii (subfamily Gastrosaccinae) and Neomysis awatschensis (subfamily Mysinae) are described. The testes of both species include a pair of central cords (spermatogonial cells), two sets of lateral sacs, and a set of dorsal-lateral spermatidic pouches in which spermiogenesis takes place. Mature sperm exit dorsally from the pouches into a common U-shaped seminal vesicle, the arms of which extend posteriorly as the right and left vasa deferentia.The emphasis of this study was on the follicle cell-spermatid relationship. Spermatids retain their own cell membranes as do the follicle cells. A bundle of sperm tails extends toward the follicle cell nucleus making several revolutions about the nucleus. Masses of rodlets occupy this tract with the spermatid tails. The tail consists of an outer cylinder with banding in a periodicity similar to collagen protein, and an inner cavity filled with a structureless, dark-staining material. Heads of the spermatozoa differ considerably between the two species. The elongate, reflexed head of Neomysis with its central filament joins the tail at an acute angle. The short cylindrical head of Archaeomysis with its anterior hood-like extension joins the tail directly. The distinctiveness of the sperm types might prove useful for taxonomic purposes. As noted by previous investigators, the number of spermatids per follicle cell shows specificity: Neomysis awatschensis has around 16 spermatids per follicle cell, Archaeomysis grebnitzkii about 100.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 143 (1974), S. 349-363 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The sensory innervation of the mandibular stylets of the aphid Brevicoryne brassicae (L.) has been examined by electron microscopy. Two groups of sensory neurones are present in the mandible. Each has two neurones, one with a short dendrite extending into the base of the mandible and ending in the base and another with a long microtubular process which extends 500 m̈ down to the distal tip of the mandible. The two neurones are enclosed by an ensheathing cell comparable to the trichogen cell enveloping the group of neurones innervating pegs and hairs. This ensheathing cell is supported by extensive electron-dense filaments to form a scolopale and is embedded in the mass of stylet-forming cells at the base of the mandible. The inner segments of the dendrites are anchored to the ensheathing cell by desmosome junctions. Desmosome junctions also bind the microtubular outer segments of the short and long dendrite to each other. There is no evidence of a dendritic sheath enclosing the distal portion of the short dendrite which ends while still in the extracellular space within the ensheathing cell. The microtubular process of the long dendrite extends down the lumen of the mandible enclosed by a close-fitting extracellular sheath which penetrates and is attached to the cuticular wall of the mandible tip. Distally this sheath is thickened on one side. Deflection of the mandible would therefore deform the dendritic membrane asymmetrically because the thin walls of the sheath would bend more than the thick walls. This would exert an unequal mechanical strain on the dendritic membrane which could result in depolarization in response to deflection in a particular direction. The arrangement of the dendrites and their sheaths within the mandible is such that deflection to the right would distort one dendrite in the same way as deflection to the left would distort the other.
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