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  • Weizen
  • Cell & Developmental Biology
  • 1965-1969  (922)
  • 1925-1929  (197)
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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 127 (1969), S. 1-5 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Tooth attachment in the majority of the bony fish is by ankylosis or fibrous membrane. However, in one group of the osteichthys, the trigger-fish or balistids, tooth attachment is by means of a periodontium composed of a shallow alveolar socket, a periodontal ligament and acellular cementum.Histologically, the balistid periodontal ligament is composed of a dense fibro-cellular connective tissue possessing an abundance of typical fibrocytes, collagen fiber bundles, and oxytalan fibers. The collagen fiber bundles which resemble the principal fiber bundles of the mammalian periodontal ligament are inserted into the bone of the shallow alveolar sockets and are anchored to the teeth by means of a layer of amorphous acellular cementum that covers the radicular dentin. No cementoblasts were found in functional teeth, and epithelial rests are lacking. The mid-central zone of the balistid periodontal ligament is occupied by small blood vessels.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 127 (1969), S. 151-161 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Dense bodies in the heart muscle of Venus mercenaria exist in two forms, free and attached. Free dense bodies morphologically consist of fascicles of thin filaments in parallel array and bound together by a dense, amorphous proteinaceous material. The binding of dense bodies to the cell membrane is effected via connecting filaments of the amorphous material of the dense body which join a condensation of morphologically similar material attached to the inner osmiophilic layer of the unit membrane. This composite of dense body, connecting filaments, membrane condensation and unit cell membrane has been termed collectively the attachment plaque. The attachment plaque is part of an extensive network on the cell surface which obligates that surface to a role in the contractile process. Moreover, this set of attachment plaques imposes an organization and an orientation to most thin filaments of the cell and preserves the contractile axis of the cell.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 127 (1969), S. 163-175 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A fine structural study of the ventricular muscle of Venus mercenaria has revealed that it is an invertebrate smooth muscle. In the relaxed state induced by acetylcholine, both thick (350 Å) and thin (80 Å) myofilaments are observed. These are loosely distributed in bundles in the periphery of the mononucleated myocytes. The central core of the cell contains an ovoid nucleus, α-glycogen rosettes, round mitochondria and numerous smooth surfaced vesicles of the endoplasmic reticulum. After exposure to serotonin, all myofilaments are compacted in the peripheral cytoplasm and become oriented parallel to the longitudinal cellular axis. This produces contraction bands visible in phase contrast microscopy. Because these myofilaments attach to the cell membrane at sites of attachment plaques, contraction of the cell results in the serial evagination or blebbing of the cell surface. The above features are clearly demonstrable in this invertebrate smooth muscle and strongly suggest a sliding filament model as the contractile mechanism in this tissue. Moreover, the cell surface is thought to play an active and major role in that process.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 127 (1969), S. 233-257 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: There are eight retinula cells in the ommatidium of the compound eye of the toadbug (Gelastocoris oculatus), two of which are central in position. Along the axial sides of the six peripheral retinula cells expand six cytoplasmic processes from the apical crystalline cone cells. These processes, which contain longitudinally-oriented microtubules, are associated with all eight retinula cells by means of desmosomal junctions. In addition to providing structural support, the possibility is set forth that the interconnecting cone processes might also serve to functionally integrate the retinula cells of an ommatidium. The eight retinula cells possess microvillus surfaces, which are especially prominent in the six peripheral cells, where they extend into the lumen of the ommatidium. There is evidence of pinocytotic activity at the bases of microvilli. Multivesicular bodies are present in the cytoplasm of retinula cells, and the means by which these bodies might be elaborated are discussed.
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  • 5
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Normally, urodele limb regeneration is nerve-dependent. Reduction in nerve-dependency has been reported for regenerating, transplanted newt limbs (Singer and Mutterperl, '63). Aneurogenic limbs can regenerate without nerves (Yntema, '59). Induction of supernumerary limbs may be obtained from aneurogenic limbs of larval Ambystoma after transplantation orthotopically to innervated larvae and with normal nerve ingrowth to the limb transplant prevented by repeated section of brachial nerves. Of the 13 (of 43) grafts with supernumeraries, nerve counts showed 11 with 0-5; 1 with 5-10; and 1 with 20+ fibers. Orthotopically grafted aneurogenic limbs allowed to become innervated showed 14 supernumeraries in 49 grafts. This supernumerary limb induction is thus not nerve-dependent.Normally, innervated larval Ambystoma limbs grafted orthotopically and heteroplastically regenerated in 17 of 37 cases after repeated section of brachial nerves. Of the 17 regenerates nerve counts showed 4 with 0-5; 5 with 5-10; 7 with 10-19; and 1 with 20+ fibers. Larval limbs heteroplastically transplanted may require very few or no nerves for regeneration.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 127 (1969) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 127 (1969) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 8
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A structure for a generalized insect epidermal cell during the formation of the epicuticle is proposed, based on studies of several different epidermal cell types. The protein epicuticle is defined as the dense homogeneous layer below the cuticulin. The formation of the protein epicuticle involves secretory vesicles arising in Golgi complexes, and marks an interlude in the involvement in cuticle formation of plasma membrane plaques. The plaques are concerned in cuticulin formation before and in fibrous cuticle formation after the deposition of the protein epicuticle.The epidermis is characterized by the possession of a cytoskeleton of microtubules and a matrix of microfibers. In the elongated cells forming bristles and spines, the microfibers are often oriented in bundles with an axial banding which repeats every 120 Å. The microtubules are also arranged in columns with a trigonal packing and center to center spacing of about 800 Å. These cytoskeletal structures separate the other organelles into channels which may restrict the pathways open for the movement of secretory and pinocytotic vesicles. The protein epicuticle arises from the secretory vesicles which discharge at the apical surface. The contents disperse and reaggregate below the cuticulin. The Golgi complexes in the basal and central regions have many secretory vesicles and a small saccular component, differing from those nearer the apex which are smaller and have fenestrated saccules. The small coated vesicles (800 Å in diameter) associated with both sorts of complex, probably move to the apical and basal faces of the cell where they may give rise to the large coated vesicles (2000 Å in diameter) inserted in the plasma membrane. Pinocytosis occurs from both apical and basal faces but most lytic activity is in the apical region. Plant peroxidase injected into the haemocoel is taken up basally and transported to the apical MVBs. The large coated vesicles on the apical face may be concerned in the control of the extracellular subcuticular environment. They appear to fill up and detach, fusing to become the apical MVBs.
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  • 9
    Electronic Resource
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 127 (1969), S. 105-112 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A detailed description of the innervation of the individual muscles of the antenna of the centipede Scolopendra morsitans is given. There are six nerves supplying the antennal muscles of each side. The nerve N I consists of 26 bundles of which two are motor, 12 sensory and 12 are mixed. It innervates the intrinsic muscles of the antenna and the antennal sense organs. The nerves N II, N III and N IV innervate the dorsal extrinsic muscles and the nerve N V and N VI the ventral extrinsic muscles.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 127 (1969), S. 73-104 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Development of the adult fly foot falls into clearly defined phases of cell division, growth, cuticle secretion and cell death. The pulvillus is composed dorsally of two giant cells and ventrally of thousands of minute tenent cells; the former produce the dorsal footpad cuticle and the latter the thousands of tenent hairs. Cell divisions are still occurring in future tenent cells when increase in size of the cells and in polyteny of the chromosomes is already occurring in the two dorsal cells. Also cell death occurs considerably earlier in the tenent cells, yet the sequential secretion of some six cuticular layers takes place at comparable times in dorsal and ventral cuticles. The cuticular layers formed are, in their order of secretion: ecdysial membrane, cuticulin of the epicuticle, dense exocuticle, homogeneous exocuticle, an intermediate layer, wax of the epicuticle, and an extensive mass of endocuticle. The ecdysial membrane seems to perform an important mechanical role in maintaining the shape of the delicate cytoplasmic projections of the tenent cells, before and during cuticle secretion, and in establishing the cuticular pattern of ridges in the dorsal cuticle. Comparisons are made with trichogen cell cuticle development and with tracheal cuticle. Tracheal, trichogen and dorsal footpad cuticle patterns are compared.Details of giant cell activity provide a working basis for studies of nuclear-cytoplasmic interactions, and the whole system raises many unsolved problems in the general field of cell differentiation and pattern formation.
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  • 11
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 127 (1969) 
    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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  • 12
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Oogenesis and embryonic development in the marine sponge, Haliclona ecbasis, were studied using standard histological procedures.When the oocytes reach a diameter of about 30 μ, nurse cells begin to aggregate around them. Then when the oocytes are about 36 μ in diameter, they begin to engulf the associated nurse cells. Whole nurse cells are engulfed; and although the nucleus of the nurse cells disappears either as or soon after the cells are engulfed, the cytoplasm remains essentially unchanged. The accumulation of these cells within the oocytes most of the cytoplasm is nurse cell cytoplasm.During cleavage of the egg, the engulfed nurse cells are gradually fragmented, but otherwise appear unchanged. At the same time the cytoplasm of the nurse cells is progressively incorporated into that of the blastomeres by what appears to be fusion process. When the latter process is complete, the embryo develops into a typical parenchymula larva.
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  • 13
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The venom system of Nasonia vitripennis is well-developed and composed of an unbranched acid gland and associated reservoir. Fine-structural, histochemical and electrophoretic studies indicate that the venom is produced by two protein-secreting epithelia. The bulk of the venom is synthesised in the columnar cells of the acid gland and discharged via “vesicular organelles” and the efferent ductular system into the lumen of the reservoir. The acid gland also contains squamous chitogenous cells, situated either around the central lumen or interposed between the bases of the columnar cells. Once within the reservoir, the venom is probably activated by enzymatic secretions from the reservoir secretory cells. Each of these cells has a “vesicular organelle” but, in contrast to the columnar cells of the acid gland, the cytoplasm contains a preponderance of free ribosomes, and protein segregation apparently occurs outside the Golgi complexes.The venom is expelled through the efferent discharge duct by muscular contractions, which open the duct lumen and bring it into contact with the funnel of the ovipositor. Excessive distortion of the duct is prevented by a massive ventral ligament.
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  • 14
    Electronic Resource
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 127 (1969), S. 431-438 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The vitelline cells in Gorgoderina attenuata produce two qualitatively distinct substances. One substance assumes the form of individual, dense, osmiophilic globules. Many globules are contained in a single vesicle. The other substance is an amorphous mass of medium density that completely fills a vesicle.Observations indicate that the dense, osmiophilic globules develop in association with a system of small, contiguous, ribosome-free vesicles. It is suggested that this system of vesicles constitute a Golgi apparatus for these cells.The amorphous mass substance develops in vesicles which appear to be derived from endoplasmic reticulum. Close association between the amorphous mass vesicle and mitochondria are commonly observed.
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  • 15
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The ventral lobe of the adenohypophysis of the smooth dogfish, Mustelus canis, a viviparous elasmobranch, has been found to possess distinctive cells identified as basophils on the basis of staining properties. At maximum size, such a cell consists of a distended vesicle containing PAS-positive, AF-negative material surrounded by a thin envelope of cytoplasm and an eccentric nucleus. In earlier stages of these cells, vesicles are small or absent and granules in the more abundant cytoplasms are AF or Alcian-positive.Basophil numbers are high in pre-ovulation and mid-ovulation females, decrease markedly after the end of ovulation until embryos are about 1 cm long then increase greatly during August and September while embryos grow to 8 cm in length. Early high counts, if these basophils are gonadotropes, may be correlated with stimulation of the ovary and ovulation; reduced numbers suggest inhibition, possibly by ovarian hormones for a period, while subsequent increase may indicate indirect involvement in uterine conditions in this viviparous species. Conclusion are, admittedly, tentative as specimens were available during only a fraction of the ten month gestation period.
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  • 16
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Submandibular glands of the opossum have been studied by light and electron microscopy and compared with other mammalian salivary glands. The glands have four parenchymal segments which connect in the order named below to convey saliva toward the oral cavity. 1Secretory units are elongated branching tubules exhibiting mucous and special serous cell types. Mucous cells predominate and resemble those in other salivary glands. Special serous cells differ from “typical” serous cells. They contain a preponderance of tubular or vesicular endoplasmic reticulum and secretory granules which vary from electron lucent to electron opaque.2Intercalated ducts are short segments lined by nonsecretory, cuboidal cells.3Striated ducts are numerous and lie in the center of the lobule. The duct epithelium has four cell types, designated light cells, dark cells, Type I basal cells, and Type II basal cells. Light cells possess basal infoldings associated with mitochondria, but the other cell types lack this characteristic.4Excretory ducts are also lined by four cell types which bear the same names as those of striated ducts. Three of the four cell types are virtually identical to those of striated ducts, but light cells differ. They do not always contain basal infoldings and the supranuclear cytoplasm lacks distinct inner and outer zones.The glands resemble salivary glands of higher mammals in many respects while possessing certain unique cytological features which may reflect the secretory needs of the organism.
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  • 17
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Several biological distances based on cranial and mandibular variation among breeding groups of white-tailed deer were calculated and compared with geographic distances among the groups. Distances based on epigenetic variation among ten groups were calculated using 16 non-metric variants of the cranium and mandible. Penrose's size and shape distances and Mahalanobis' D2 distance were calculated for 11 groups; the calculations were based on seven skeletal and seven dental metric variables of the mandible.The biological distances were correlated with geographic distance as follows: the epigenetic distance, 0.74; Penrose's shape distance, 0.71; Penrose's size distance, 0.45; and Mahalanobis' distance, 0.37. All correlations were significant at the 0.01 level. The epigenetic and Penrose shape correlations were significantly higher than the Mahalanobis correlation.Because of the conditions under which the breeding groups were selected, it was assumed that genetic affinites among the groups would be a function of geographic distance. The results suggest that the epigenetic distance and Penrose's shape distance reflect genetic affinities among groups better than do the Penrose size and Mahalanobis distances.
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  • 18
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Hearts of the Atlantic hagfish, Myxine glutinosa were studied with the electron microscope after prefixation in phosphate buffered glutaraldehyde or buffered formalin and subsequent postifxation in phosphate buffered osmium tetroxide. Epicardial, myocardial and endocardial layers are identified; however the hearts of Myxine lack an extensive capillary system comparable to the coronary vessels of other vertebrate heart tissues. Instead, blood is supplied to cells via an elaborate system of channels which extend between numerous trabeculae that make up the cardiac wall of this organism. Fine structural features of special interest include the presence of numerous dense granules (chromaffin granules) within myofibers and also specific granular cells which lack the contractile elements that are characteristic of both skeletal and cardiac myofibers. Another prominent feature noted includes an elaborate system of tubular invaginations within the subjacent sarcoplasm. These elements appear to be specific for the myofibers. They are continuous with the plasma membrane and project into the peripheral sarcoplasmic matrix. Crystalline inclusions are also observed in the sarcoplasm of the myofibers. These are compared with similar inclusions in other cellular components. The Golgi complex is very extensive in the myofibers of Myxine, and granules of varying sizes and densities often appear in the vicinity of the Golgi saccules. The observations suggest that the numerous vesicles around the Golgi Complex represent intermediate stages in the formation of the chromaffin granules. The structure and function of the extensive tubular invaginations are compared with the transverse tubules reported in several mammalian heart tissues.
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  • 19
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Structural and functional changes have been correlated during metamorphic degeneration of a single muscle fiber, the plantar retractor of G. mellonella, its axon, and their junctions to determine which features persist as long as muscle contractility. Changes commence simultaneously in muscle and nerve near cuticular attachments, and spread towards the center. Alterations associated with the muscle, including appearance of collapsed tracheoles and mitochondria with dense bodies, begin late in the last larval instar. Within 12 hours after pupal ecdysis some tracheolar withdrawal occurs, sarcoplasmic reticulum becomes reduced, and many mitochondria have dense bodies, dense membranes, or are enlarged. By 17-19 hours primary myofilaments and striations begin to disappear, microtubules and autophagic vacuole-like bodies appear, and phagocytes invade the muscle. It remains partially contractile upon electrically stimulating its nerve, the ventral nerve, until these changes spread throughout the fiber.Neuromuscular junction changes, including appearance of dense mitochondria and isolation bodies, begin late in the last larval instar. Junctions become fewer, and none remain in those muscle areas where tracheoles, sarcoplasmic reticulum, and primary myofilaments have disappeared.Preliminary studies on nerve discharge activity to the muscle suggest that nerve silence occurs at approximately the time when the muscle loses all contractility. In some axons isolation bodies appear and neurotubules are lost, other axons remain unchanged, and new ones develop later in the pupal state. Phagocytes invade the neural lamella and it disappears in the late pupa, but it reappears in the adult.The adult ventral nerve has over three times more axons and a thinner layer of glial cells than the larval nerve.
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  • 20
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The purported “neoblasts” of the serpulid Spirorbis have been studied in Spirorbis (Paradexiospira) vitreus and Spirorbis (Laeospira) borealis at both the light and electron microscopic levels. These perivasal cells occur in greatest abundance around the ventral blood vessel of the achaetous region. In light microscope preparations, the perivasal cells are intensely basophilic, containing basally situated nuclei, and relatively large nucleoli. The fine structure of the perivasal cells reveals that they contain an abundance of rough endoplasmic reticulum, well-developed Golgi complex, heterogeneous dense bodies, and cytolysomes. The respiratory pigment chlorocruorin, which has a diameter of about 230 Å and is believed to be composed of two superimposed hexagonal components, has been localized within: cisternae of the rough endoplasmic reticulum, elements of the Golgi complex, and membrane-bounded vesicles at the base of the perivasal cells. Evidence is advanced which strongly suggests that molecules of chlorocruorin are transported from the perivasal cells into the lumen of the vessel by reverse pinocytosis. It is concluded that whatever other functional role(s) the perivasal cells of Spirorbis may have, a major function is the synthesis and secretion of chlorocruorin. Whether the perivasal cells can be considered to be pluripotent is discussed.
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  • 21
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 128 (1969), S. 309-363 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The hands of the Hominoidea evidence four adaptive modes which distinguish the lesse apes (Hylobatidae), the orangutan (Pongo), the African apes (Pan), and man (Homo) from one another. The hands of the apes consist of compromises between manipulatory and locomotor functions because selection has operated for precision of grip as well as for special locomotor mechanisms. The human hand is almost totally devoted to manipulation. The hands of gibbons, orangutans and the African apes differ in many features that may be correlated with locomotion. The gibbons and siamang are specially adapted for ricochetal arm-swinging. The great apes possess morphological adaptations for arboreal foraging and climbing distinct from those of the hylobatids. In addition, the African apes have become secondarily adapted for terrestrial quadrupedal locomotion. Many features that distinguish the hands of chimpanzees and gorillas may be associated with the development of efficient knuckele-walking propulsive and support mechanisms.
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  • 22
    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 the thyroid of the newt, Notophthalmus viridescens, was studied with the electron microscope. Specimens were injected I.P. with 30 μc of I131 and sample thryoids were examined at 12 hour intervals thereafter. The ultrastructure of the normal thyroid gland is described, and compared with that of the irradiated glands. The first visible ultrastructural change observed after injection of the radioiodin was a striking alteration of nuclear morphology. This effect was followed by an increase in the frequency of whorled lamellar structures, a decrease in the number of microvilli, and degeneration of the Golgi apparatus and endoplasmic reticulum. Further effects observed included an increase in the number of large cytoplasmic granules and a decrease in the number of smaller ones, the presence of autophagic vacuoles, and finally, an increase in the number of degenerated mitochondria.
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  • 23
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 128 (1969), S. 443-463 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The campaniform sensilla on halteres of Drosophila were studied by electron microscopy in order to establish the relationships of functional elements in the sensory system. The surface of the sensillum consists of an oval cuticular cap membrane which may contain resilin, the rubberlike protein. A border of denser cuticle rings the cap membrane, and extending down around the neural process is a third type of cuticle filled with a fourth light fibrous type. The four cuticular components form a system for displacement of the neural process. The neural process is differentiated into a terminal fan-shaped structure projecting from a bulbous dilatation which tapers to a neck region ending proximally with two basal bodies. The neural process is packed with microtubules. Surrounding the dendrite is an inner enveloping cell, attached to the basal body region by septate desmosomes and by desmosomes to which microtubules of the enveloping cell are applied. An outer enveloping cell surrounds the inner one. The tip of the neural process is covered with a dense secretion which is tightly bound to the cap membrane. The dense secretion is surrounded by an extracellular fluid which might be compressed hydraulically by the cuticular system. The stimulus of cuticular distortion could thus be transmitted to the neural process which may be displaced between its fixed ends.
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  • 24
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The fine structure of the mid-gut epithelium and regenerative cells of larvae of a moth (Ephestia kühniella) is described. Particular attention is paid to the absorptive and goblet cells and their lateral junctions; these features are discussed in terms of the digestive and regulatory functions of the epithelium. One digestive pathway has been investigated with the aid of ingested ferritin; intake of this marker by endocytosis and the evident involvement of Golgi vesicles in the transformation of endocytic vesicles into multivesicular bodies, together with the fate of the latter, are discussed in terms of the digestive function of this part of the alimentary tract and of the lysosome concept.
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  • 25
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Each statocyst in Apylsia californica contains 13 neurons. The statocyst nerve, which connects each statocyst to the cerebral ganglion, contains only the 13 axons of the statocyst neurons. The size of the statocyst, the number of neurons in the statocyst, and the average axonal diameter does not change even though the statocyst nerve lengthens greatly as the animal enlarges. A description of the statoconia and the supporting cells in this organ has been given. This prepazation may be useful for microelectrode studies designed to test whether the gap and cytoplasmic specializations that are used to identify active synapses, are necessary for all types of chemical synaptic transmission.
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  • 26
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 127 (1969), S. 205-223 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Large quantities of colloidal particles were rapidly transported around the junctional complex into the lateral intercellular spaces by flounder renal epithelial cells. Large invaginations containing particles developed in the apical cytoplasm of cells when tracer particles were injected into the tubular lumens. Some membranebounded profiles containing particles appeared close to the lateral intercellular spaces. Particles were then found in the lateral intercellular spaces, between the basal plasmalemma and the basement membrane, and within the basement membrane. It is suggested that this transport might operate in situ and provide a morphological mechanism to explain a type of protein transport noted in the renal tubules of another flounder species by Maack and Kinter ('67). It is interesting to consider that perhaps a similar mechanism for the transport of intact proteins might also operate in mammalian nephrons as well.
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  • 27
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    Journal of Morphology 127 (1969), S. 341-353 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Three-dimensional, histological, and x-ray techniques provide a picture of body segment and limb morphogenesis. Cell multiplication begins in the proliferation region (“meristem”) during the molt from the preceding instar. By four days post-molt, the cells that will form the new segments are well under way in their anterior, lateral, and dorsal migration. It is suggested that after the anlagen for all the new segments are estabilshed, a mitotic wave commences in the most anterior anlagen and moves posteriorly during the remainder of the instar. When cell proliferation is complete, final differentiation of the segments takes place.The process of limb formation is one of cell proliferation and perhaps migration. Each limb develops in a membranous pocket during the instar following the one in which its respective body segment was formed.
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  • 28
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Using the Colcemid technique, the mitotic incidence (MI) was measured in the epidermis, lung, spleen, liver, kidney and ovarian follicular cells of metamorphosed, immature Xenopus laevis laevis. The MI was higher at 25°C than at 20°C, and there was a significant ranking correlation between organs in respect of the MI in different animals. With the exception of the liver and kidney, organ cultures showed good preservation for up to six days in vitro using a medium supplemented with 10% fetal calf serum, and values for MI comparable with or even higher than in vivo were obtained.
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  • 29
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    Journal of Morphology 127 (1969), S. 409-429 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The developmental cytology of the apical tissue of the testis of Tenebrio molitor and Zophobas rugipes was studied with light and electron microscopy. In the early larvae of both species the tisue was found to be a thickened protrusion of nongerminal cells appearing at the apical end of each testis follicle following gonadal differentiation. The cells persist through pupal and adult stages in both species, becoming more prominent at these stages in Z. rugipes, despite tracheal invasion in both species. In older adults the apical tissue regresses and ultimately distintegrates.Ultrastructurally the apical cells are distinguished from adjacent germinal cells by their (1) small, rounded or oval nuclei, (2) highly convoluted plasma membrane, (3) electron-opaque cytoplasm, (4) profuse concentrically-stacked, granular endoplasmic reticulum, (5) large aggregates of glycogen-like granules, (6) numerous small, tubular mitochondria, (7) well-developed Golgi centers and (8) striking arrays of microtubules. These cells have many cytological features in common with the androgenic gland cells of crustaceans, but not with the steroidogenic cells of vertebrates. Evidence for the formation of protein granules is also lacking. As yet, experimental procedures have not indicated an endocrine function for these cells in tenebrionids. However, their cytology is consistent with secretory activity of some kind.
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  • 30
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    Journal of Morphology 128 (1969) 
    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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  • 31
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In the annelid Enchytraeus albidus the ovary is composed of packets containing eight synchronously developing oocytes. Each oocyte in the packet is connected, via a bridge, to a common cytoplasmic mass. Developmental synchrony of oocytes within individual packets is probably related to the ooplasmic continuity.The young previtellogenic oocyte contains many polysomes, a few cisternae of smooth and rough endoplasmic reticulum, small Golgi complexes, and mitochondria. Many of the mitochondria are dumbbell-shaped and may thus represent division stages.Vitellogenesis is marked by the appearance of peripherally located lipid yolk and small, densely staining granules scattered throughout the ooplasm. There is an increase of smooth endoplasmic reticulum, mitochondria, and enlarged Golgi elements. Small multivesicular-like bodies, the early stages of developing yolk, are derived from the Golgi complex. The mature yolk sphere is bipartite and consists of (a) a variable number of dense spheres, the core bodies, which are produced in the ooplasm by the Golgi complex and which become embedded in (b) a dense matrix. The electron opaque tracer, horseradish peroxidase is incorporated into the oocyte and deposited in the matrix suggesting that this component of the yolk sphere is obtained by micropinocytosis. Enzyme digestions and various cytochemical techniques suggest that the core bodies are rich in carbohydrate, probably as glyco- or mucoproteins, and that the matrix is rich in lipid.
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  • 32
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    Journal of Morphology 128 (1969), S. 67-93 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The endoskeletal structure supporting the gill-books of Limulus polyphemus has been investigated by means of light and electron microscopy, chemical analysis and x-ray diffraction. This tissue is a cartilage which has significant correspondences with both vertebrate cartilage and plant tissues. Morphologically, the Limulus cartilage resembles certain cellular vertebrate cartilages with relatively scant matrix, and also certain plant parenchyme, collenchyme and sclerenchyme tissues. Of particular interest, was the observation that during cytoplasmic division, a phragmasome-like structure appears between the daughter cells of the dividing gill cartilage cells. This phragmasome-like structure appears to be a precursor of new matrix (cell-wall) formation between the young chondrocytes, in much the same fashion as its counterpart in plant tissues. Perichondrial cells and underlying chondrocytes contain lipid droplets, abundant glycogen and ribosomes, as do corresponding vertebrate cartilage cells. In some of the Limulus cells, glycogen and ribosomes appear to be admixed with lipid, forming aggregates in which all three materials are in intimate intraparticulate relationship. During molting, the number of ribosomes seen in chondrocytes increases. The tissue contains both hydroxyproline and hydroxylysine, and gives a weak x-ray diffraction pattern.
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  • 33
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    Journal of Morphology 128 (1969) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 34
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The ultrastructure of mouse tracheal epithelium was examined. The three cell types, basal cells, ciliated cells and goblet cells, described for other mammalian trachea were found to be present although goblet cells occurred only rarely. A cell type, termed the nonciliated cell, not described in other mammalian trachea was frequently found in mouse tracheal epithelium. These cells contained abundant smooth and rough endoplasmic reticulum, free ribosomes, a large Golgi complex, and many mitochondria. There were many vesciles containing an electron dense material near the luminal surface of these cells; these cells were positive for PAS. These features suggested a secretory function for the cells. This, along with the scarcity of goblet cells, suggested that the nonciliated cells of mouse tracheal epithelium fulfill the function of the goblet cells found in other mammalian trachea.
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  • 35
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    Journal of Morphology 128 (1969) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 36
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Ampullary receptor organs of the South American weakly electric gymnotid fish Eigenmannia virescens consist of a pore at the surface of the skin, a canal through the epidermis, and the expanded basal end of the canal in the corium. The cavity of the organ contains a jelly that is filled with fine fibers. The canal wall consists of three to six layers of flattened cells that appear to be derived from the adjacent skin. Along the lumen of the organ the cells are joined by tight junctions. Usually there are four spherical receptor cells in the base of the organ. They are innervated by single neural terminals. These organs are compared to tuberous receptor organs found in the same species, and the functional significance of the fine structure observed in these cells is discussed.
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  • 37
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The concept of functional components was initially proposed by van der Klaauw ('45, '52) to indicate overlap of functional influences particularly in mammalian skulls; his analysis marked a departure from the study of single characters to that of function-modified systems. A very similar set of terms is now coming into vogue to describe the mechanically separable components of highly kinetic fish, amphibian and reptilian skulls. In these cases the term functional unit often pertains only to the musculo-skeletal system and is utilized during the process of description; it is often applied before a complete functional analysis has been carried out.Yet, any structure tends to be affected by the influence of multiple functions, and any function will almost certainly affect multiple characteristics of the animal. Since functional components overlap, the term should not be used to label an essentially topographical dissection of the animal. It cannot be expected that each loosely connected component of a kinetic skull subserves as a single “function,” and that this function does not overlap onto other units.It is suggested that the term mechanical unit be substituted as a label for the mechanical sub-divisions often utilized to organize descriptions. The concept of functional units in the original sense then remains available as an analytical tool.
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  • 38
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A detailed topography of adrenergic innervation in invertebrates (lobster), low vertebrates (fish, amphibians, reptiles, birds), and nine species of mammals is presented. Flack and Hillarp's specific fluorescent histochemical method using freeze-dried material was used. Phylogenetically, adrenergic innervation appeared earlier under the ciliary epithelium and in the muscle than surrounding the vessels, and in all species many fibers were without any connection to the vessel walls. Adrenergic innervation was very rich in the dilator muscle extending toward the epithelium of the posterior chamber; a surprisingly rich network was found in the sphincter muscle and also in ciliary spaces of some species. Numerous fluorescent mast cells were visualized in the pecten of the bird eye and in the ciliary tissue of the sheep and cow.
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  • 39
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In order to obtain more direct evidence for the occurrence of myoblast fusion in the developing amphibian embryo, the following transplantations were performed in vitro. The nuclei of early embryos. Ambystoma tigrinum and A. maculatum, were labeled with tritiated thymidine. Portions of prospective somite areas from these labeled donors were grafted homoplastically and orthotopically into unlabeled hosts of the same, or nearly the same, stage. The stages employed were: neurula, early tail bud, and late tail bud. Hosts were raised until they had developed into more advanced larval forms, fixed, sectioned, and prepared for radioautographic processing according to the customary procedures.The histological preparations contained varying numbers of multinucleate myotubes of a “composite” nature: that is, individual myotubes contained labeled nuclei of the donor, side by side with unlabeled nuclei of the host. There was no doubt that the mononucleate myoblasts of the grafts had fused with those of the host species to form the mutlinucleate composite myotubes.In addition to the above determinations, the method of thymidine labeling has proven to be a satisfactory method of tracing, in the context of the intact organism, somitic cell derivatives up to the feeding larval stage. Mesenchymal cells from the grafted labeled somitic tissues were consequently found in: dermatomic, sclerotomic and intermyotomic locations; the matrix of the dorsal fin; the limb bud; the abdominal muscles.
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  • 40
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The cecropia moth oocyte accumulates proteins from the blood during vitellogenesis; the proteins reach the oocyte by an intercellular route, are taken in by pinocytosis, and become components of the protein yolk spheres. Different proteins vary greatly in the extent to which they are incorporated into the yolk spheres. One objective of the work described in this paper was to determine where the selectivity of protein uptake occurs. An autoradiographic analysis of the uptake of tritiated blood proteins injected into the hemocoel indicated that there are at least two sites of selectivity - one between the hemocoel and the intercellular spaces of the follicular epithelium that surrounds each oocyte, and another between the intercellular spaces and the yolk spheres. Another objective was to determine if only proteins from the blood are deposited in the protein yolk spheres. Studies of the incorporation of tritiated leucine provided evidence that the ovary itself synthesizes proteins that are deposited in the yolk spheres along with the blood proteins. Finally, evidence is presented that the various regions of the oocyte cortex are not equally active in the deposition of yolk.
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  • 41
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    Journal of Morphology 129 (1969), S. 81-87 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The interstitial cells of Pennaria tiarella differentiate exclusively from the central endoderm of the planula. Shortly after their appearance, most of the interstitial cells become cnidoblasts. Subsequently, as the larva transforms into a polyp, both cnidoblasts and interstitial cells migrate from the endoderm, through endoblast and mesoglea, into the ectoderm. It is suggested that some interstitial cells remain in the endoderm and differentiate into the gland and mucous cells of the polyp gastroderm.
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  • 42
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Differentiating oocytes and associated follicle cells of two species of amphineurans (Mollusca) Mopalia muscosa and Chaetopleura apiculata have been studied by techniques of light and electron microscopy. In addition to the regularly occurring organelles, the ooplasm of young oocytes contains large, randomly situated, basophilic regions. These regions are not demonstrable in mature eggs.As oocytes differentiate, lipid, pigment and protein-carbohydrate yolk bodies accumulate within the ooplasm. Concomitant with the appearance of pigment and the protein carbohydrate containing yolk bodies, the saccules of the Golgi complex become filled with a dense material. Associated with the Golgi complex are cisternae of the rough endoplasmic reticulum which are filled with an electron opaque substance which is thought to be composed of protein synthesized by this organelle. That portion of the cisternae of the endoplasmic reticulum facing the Golgi complex shows evaginations. These evaginations are thought to finalize into protein containing vesicles that subsequently fuse with the Golgi complex. Thus, the Golgi complex in these oocytes might serve as a center for packaging and concentrating the protein used in the construction of the protein containing pigment or protein-carbohydrate yolk bodies. The suggestion is made that the Golgi complex may also synthesize the carbohydrate portion of the formentioned yolk bodies.In an adnuclear position in young oocytes are some acid mucopolysaccharide containing vacuolar bodies. In mature eggs, these structures are found within the peripheral ooplasm and we have referred to them as cortical granules. There is no alteration of these cortical granules during sperm activation.
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  • 43
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Mature myoid cells in the parenchyma of reptilian thymus contain all the organelles typical of striated muscle. The presence of both immature and degenerating stages indicates a turnover of myoid cells in the adult thymus. In the earlier stages of differentiation myoid cells resemble thymic epithelial cells. A close parallel exists between developing myoid cells, skeletal muscle differentiating in vitro, rhabdomyoma and rhabdomyosarcoma. Elaborate lattice-like structures are formed by transverse tubules. These structures are compared with similar configurations which have been described in muscle and mitochondrial cristae.
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  • 44
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: An analysis of differentiating oocytes of the gastropod, Ilyanassa obsoleta, has been made by techniques of light and electron microscopy. Early previtellogenic oocytes are limited by a smooth surfaced oolemma and are associated with each other by maculae adhaerentes. Previtellogenic oocytes are also distinguished by a large nucleus containing randomly dispersed aggregates of chromatin. Within the ooplasm are Golgi complexes, mitochondria and a few cisternae of the rough endoplasmic reticulum. When vitellogenesis begins, the oolemma becomes morphologically specialized by the formation of microvilli. One also notices an increase in the number of organelles and inclusions such as lipid droplets. During vitellogenesis there is a dilation of the saccules of the Golgi complexes and cisternae of the endoplasmic reticulum. Associated with the Golgi complexes are small protein-carbohydrate yolk precursors encompassed by a membrane. These increase in size by fusing with each other. The “mature” yolk body is a membrane-bounded structure with a central striated core and a granular periphery. At maturity a major portion of the ooplasmic constituents such as as mitochondria and lipid droplets occupy the animal region while the bulk of the population of yolk bodies are situated in the vegetal hemisphere.The follicle cells incompletely encompass the developing oocyte. In addition to the regularly occurring organelles, follicle cells are characterized by the presence of large quantities of rough endoplasmic reticulum and Golgi complexes whose saccules are filled with a dense substance. Associated with the Golgi saccules are secretory droplets of varied size.Amongst the differentiating oocytes and follicle cells are Leydig cells. These cells are characterized by a large vacuole containing glycogen. A possible function for the follicle and Leydig cells is discussed.
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  • 45
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The feminine dimorph has unique structures that produce eggs, select salubrious sites for the offspring, store sperm, and void the eggs. This paper provides a time table for development of these parts in Aedes stimulans based on preparations examined at 5-hour intervals when reared at 21°C. All growths of imaginal parts proceeds independent of activities in the larval tissues.Ovaries produce the eggs in terminal follicles of the ovarioles. Besides ovarioles each ovary contains sheaths for the ovarioles, pedicels attaching them to a central canal, the calyx, ovarian sheath and muscles. Ovaries are recognizable in newly hatched larvae as caps of cells on larger masses which become part of the delivery system for eggs. Each ovary grows forward from its attachment first as a column of cells that differentiates into the several tissues by the time the insect enters pupal life. Prior accounts have considered the ovary as the whole mass of cells on each side of the hemocoel of segment 6. Only the most anterior cells recognizably distinct at the end of embryogeny are generative.The delivery system for eggs is composed of the lateral oviducts and median or common oviduct. Primordia from which the former are derived are present from the end of embryogeny and throughout larval life as two distinct parts. Two ovoid masses occur in the hemocoel of segment 6. To each of these is attached a filament extending backward to an attachment ventrally and caudally in segment 7. They are rapidly changed into definitive lateral oviducts late in pupal life. The single primordium for generating the median genital tract appears during instar 3 as a caudal ventral plate of cells in segment 8 between a pair of bilateral buds and invaginates during instar 4 to form (1) the common oviduct from a midventral pouch, (2) three spermathecae from two lateral invaginations and (3) the elaborate vaginal area. The bilateral buds form no parts of the female.The post-vaginal area or atrium with its accessory organs is derived in part from the ventral plate of segment 8 and that of segment 9. The imaginal disc in segment 9 is present at the end of embryogeny as primordial buds and ventral plate and development is delayed until early pupal life when it projects inward to form part of the atrium and pouches once to form the common opening for the duct of the accessory gland and the canal to the bursa copulatrix. The buds of this disc produce no feminine parts.During the second larval instar lateral primordia appear as a pair of shields in the anal segment. They develop slowly until pupation when they extend caudally as two flaps called “cerci” in culicid literature and this paper.
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  • 46
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Histochemical procedures for acid phosphatase in normal and lens-regenerating eyes of the urodele Diemictylus viridescens demonstrate activity in a variety of structures. In the normal urodele eye, acid phosphatase is present in conjunctival and corneal epithelial cells and associated glands, in blood vessel endothelium and posterior epithelial cells of the iris, in the anterior lens epithelium, and in the cytoplasm of the optic nerve. Acid phosphatase in the lens-regenerating eye is localized in the same structures as in the normal eye as well as in increased amounts in the corneal epithelial cells and stromal macrophages at the lentectomy wound site and in the posterior portion of the developing lens during completion of differentiation of primary into mature lens fibers characterized by loss of many intracellular organelles. On the basis of these histochemical findings, it is proposed that hydrolytic lysosomal enzymes play an important role in the processes of cellular and intracellular destruction and synthesis which occur during Wolffian lens regeneration in the urodele.
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  • 47
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Median cord development is uniform in six families of Hemiptera and five non-hemipterans. The median cord arises independently from the lateral cords and is histologically distinguishable from the latter throughout development. Intrasegmentally, median cord nuclei possess prominent nucleoli and many small chromatin granules surrounded by clear nuclear sap. This region forms what appear to be glial elements at the midline of the neuropile. Intersegmentally, a spherical clump of eight to twelve large nuclei develops surrounded by dark-staining granular cytoplasm. Each intersegmental clump migrates anteriorly into the preceding ganglionic region but degenerates soon after katatrepsis.
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  • 48
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The present investigation was undertaken in an attempt to determine the role played by the nerve in the regeneration of the lower jaw of the adult newt, Triturus viridescens. The results indicated that the number of nerve fibers normally available at the amputation surface was very low compared with that of the newt forelimb. Furthermore, denervation of the lower jaw reduced the number of nerve fibers available to an extremely low level and maintained the number at a low level for up to four weeks without intervening redenervations. The regenerative events in the denervated and amputated lower jaws were indistinguishable histologically from those in amputated jaws having normal innervation. This presented an apparent exception to the general rule that regeneration of external body parts is dependent on the nerve. Several possible explanations are proposed by which this apparent exception might be explained. The process following amputation might be an exaggerated form of wound healing and tissue regeneration which can occur in the absence of nerves. The tissues of the lower jaw might be more sensitive to the influence of those nerve fibers present. The nerve fibers themselves might be qualitatively different and thus exert a greater influence on the tissues.
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  • 49
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A rapid method for examining rat fetuses is presented. The technique consists of fixing the fetuses in Bouin's solution, serially sectioning the head, neck and lower trunk with a razor blade and doing sagittal sections of the heart after opening the thoracic cavity. Examples of sections from normal 20 day rat fetuses are given as well as some with the following abnormalities: cleft palate produced by chlorcyclizine and eye and heart malformations resulting from anti-adult rat kidney serum.
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  • 50
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    Journal of Morphology 127 (1969), S. 307-339 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A fine structural analysis of fetal mouse ovaries reveals the presence of intercellular bridges between developing oocytes. These bridges, which connect two or more oocytes, are most frequently seen prior to the dictyate stage of meiotic prophase. The intercellular connections are limited by a tri-laminar membrane which is continuous with the oocyte plasmalemma. A characteristic feature of all bridges is the presence of an electron-dense material on the cytoplasmic side of the limiting membrane. Since this dense material is a constant and conspicuous component of the entire bridge, identification of these connections is possible in all planes of section. In cross section, the bridges are usually cylindrical, while in longitudinal section, a variety of configurations are observed. Oocytes connected by intercellular bridges exhibit a highly developed Golgi complex which is frequently localized in the region of the cytoplasmic continuities. Vesicular elements, apparently derived from the Golgi, are routinely observed within the boundaries of the bridges. Other cytoplasmic organelles, including rough and smooth endoplasmic reticulum, free ribosomes and mitochondria, are also seen in these bridges. The presence of these vesicles and organelles within intercellular bridges suggests that these connections may provide a means for transfer of organelles and other substances from one oocyte to another. It may be, therefore, that intercellular bridges are important for the nourishment and maturation of certain selected oocytes as well as for the synchronization of meiotic events.
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  • 51
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The mechanism of respiration in the bullfrog has been analyzed by means of pressure recordings from the buccal cavity, the lungs and the abdominal cavity, by cinematography and cinefluorography, and by electromyography of buccal, laryngeal and abdominal muscles. Gas flow was investigated by putting frogs in atmospheres of changing argon and nitrogen content and monitoring the concentration of the nostril efflux.Three kinds of cyclical phenomena were found. (1) Oscillatory cycles consist of rhythmical raising and lowering of the floor of the mouth, with open nares. They have a definite respiratory function in introducing fresh air into the buccal cavity. (2) Ventilatory cycles involve opening and closing of the glottis and nares and renewal of a portion of the pulmonary gas. More muscles are involved and the pattern of muscular activity is more complex than in the oscillatory cycles. (3) Inflation cycles consist of a series of ventilation cycles, interrupted by an apneic pause. The intensity of the ventilatory cycles increases before this pause and decreases immediately thereafter. This results in a stepwise increase in pulmonary pressure, to a plateau (coincident with the pause) followed by a sudden or stepwise decrease.The respiratory mechanism depends on the activity of a buccal force pump, which determines pulmonary pressure whose level is always slightly less than the peak pressure values of the ventilation cycles. The elevated pulmonary pressure is responsible for the expulsion of pulmonary gas during the second phase of the next ventilation cycle. This pressure is maintained by the elastic fibers (and the smooth masculature) of the lungs.
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  • 52
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    Journal of Morphology 127 (1969), S. 355-362 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The serigenous glands of a number of different sawfly larvae have been examined. Silk is secreted by pear-shaped cells which may be fused together in pairs or triplets, or exist simply as free, single cells. The cells are arranged in numerous groups attached to a pair of wide silk reservoirs by means of short canals. Each gland cell contains a large, irregular, ramifying nucleus and an intracellular duct which receives droplets of synthesised silk protein. Two modifications of this basic arrangement are described. It is suggested that the secretory cells are dermal gland cells, and that the intracellular duct is a rudimentary end-apparatus. A comparison is made between these and some other types of dermal gland cell found in insects.
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 127 (1969) 
    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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  • 54
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The complete regeneration of a new oral-disc and tentacles has been observed and described for Aiptasia diaphana. These structures are regenerated quite rapidly: seven to ten days at 20°C. At three days post-amputation, the new primary, secondary, and tertiary tentacle buds begin to develop in direct association with the underlying primary, secondary, and tertiary septae (respectively) of the column, suggesting that the latter organize the form of the regenerating oral-disc. Two days after amputation, the zooxanthellae of the presumptive oral disc arrange themselves into a ring which quite precisely delimits the area from which the tentacle buds will form. In spite of its suggestive proximity, this accumulation of algae plays no role in the induction of tentacle buds as was shown by studying regeneration in anemones which essentially lacked large quantities of these symbiotic algae.Cuts perpendicular to the longitudinal axis of the column result in an equal rate of tentacular regeneration around the entire circumference of the presumptive oral disc. Oblique amputations foster an asynchronous regeneration: the tentacle buds of the distal-most area of the severed column are larger and regenerate much sooner than those of the proximal region. Similar results were obtained by studying anemones which were cut perpendicular to their longitudinal axes at different levels along the column. The data suggest that an oral-aboral gradient exists concerning the time required for the initiation of tentacle budding and the rate of tentacle regeneration.
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    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The structure of human labial salivary gland acini was studied by light and electron microscopy. Contrary to previous reports, these glands were pure mucous in nature; no serous elements were present. The acinar cells were found in all stages of maturation. Immature cells were characterized by an extensive and highly organized rough-surfaced endoplasmic reticulum. The Golgi complex was extremely prominent, consisting of stacks of flattened cisternae and swarms of small vesicles. Mucous droplets were almost completely absent. As secretory activity progressed, the endoplasmic reticulum involuted, while the Golgi cisternae became distended and formed many vacuoles. In mature mucous cells, the apical cytoplasm was filled with membrane-bounded mucous droplets, and the nucleus was displaced basally. The droplets frequently showed great variation in density from cell to cell, and even within the same cell they sometimes were quite heterogeneous. They were liberated from the acinar cells by an apocrine process, so that droplets with intact limiting membranes were often observed in the acinar lumen. These droplets soon lysed, their contents fusing into streams of mucus. Occasionally during apocrine secretion a mucous cell failed to reconstitute its apical surface, and its entire contents spilled into the acinar lumen.Unusual cytoplasmic inclusions were present in many of the acinar cells. These inclusions, which were surrounded by a single membrane, consisted of lipid droplets closely associated with bundles of fine filaments.
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    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Bovine parotid glands exhibit outstanding structural differences when compared with those of non-ruminant mammals. The acini are tortuous, branched and lined with cells of different heights, imparting a scalloped appearance to acinar lumina. Numerous microvilli, ca. 1.5 μ in length, extend into the lumina and intercellular canaliculi. Intercellular canaliculi measure ca. 3 μ in diameter and interweave in close association with intercellular tissue spaces. Intercellular tissue spaces are separated from the extraacinar spaces across a basal lamina only, whereas junctional complexes guard canaliculi from direct continuity with tissue spaces and/or extraacinar spaces. Flattened cytoplasmic lamellae extend from adjacent acinar cells and loosely interdigitate with one another across the tissue spaces. Acinar cells contain more mitochondria and less granular endoplasmic reticulum than parotid glands of non-ruminant mammals. Two types of secretory material, in the form of inclusions which vary in size and electron density, are present in the acinar cells. Intercalated ducts connect acini with striated ducts which in turn, empty into collecting ducts located between gland lobules. In terms of frequency of “basal infoldings” and numbers of mitochondria, striated ducts of calf parotid glands are not as well developed as those of certain other salivary glands. Myoepithelial cells are most often present at junctions of acini and intercalated ducts where they may attach to both acinar and ductal epithelium. Nerve “terminals” were not observed on the epithelial side of basement membranes in relation to the secretory cells.
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  • 57
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The secretory processes in the shell gland of laying chickens were the subject of this study. Three cell types contribute secretory material to the forming egg: ciliated and non-ciliated columnar cells of the uterine surface epithelium, and cells of tubular glands in the mucosa. The ciliated cells as well as the non-ciliated cells have microvilli, which undergo changes in form and extent during the secretory cycle. At the final stages of shell formation they resemble stereocilia. It is postulated that the microvilli of both cells are active in the production of the cuticle of the shell.The ciliated cell which has both cilia and microvilli manufactures secretory granules which arise from the Golgi complex in varying amounts throughout the egg laying cycle. Granule production reaches its greatest intensity during the early stages of shell deposition. The ciliated cell probably supplies proteinaceous material to the matrix of the forming egg shell.The non-ciliated cell has only microvilli. Secretory granules, containing an acid mucopolysaccharide, arise from the Golgi complex. Some granules are extruded into the uterine lumen where they supply the egg shell with organic matrix. Others migrate towards the supranuclear zone. Here a number of them disintegrate. This is accompanied by the formation of a large membraneless space, which is termed “vacuoloid.” Subsequently the vacuoloid regresses and during regression an extensive rough endoplasmic reticulum with numerous polyribosomes of spiral configuration appears. It is suggested that material in the vacuoloid originating from the disintegrating granules is resynthesized and utilized for the formation of secretory product.The uterine tubular gland cells have irregular, frondlike microvilli. During egg shell deposition, these microvilli form large blebs and are probably related to the elaboration of a watery, calcium-containing fluid.
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  • 58
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A principal component analysis revealed that the two major components of mandibular shape variation among individuals within breeding groups of white-tailed deer in Canada and the United States involve contrasts between the mandible and the dentition and between the premolars and the molars. Size variation appeared to account for 34% of the total variation within the groups, and the two major shape variations accounted for 23% and 8% respectively.A canonical analysis was used to identify the major components of mandibular variation among the breeding groups and to provide measures of the proportion of the total variation accounted for by each component. Among male groups, size variation was associated with latitude, and the major shape variation was closely associated with longitude, so a bivariate plot of the first two canonical variates reflected the general geographic orientation of the populations.The mandibular size in a Tennessee population that descended from Wisconsin and Michigan ancestors appears to have not decreased appreciably in the more southerly habitat after introduction more than 20 years ago. Changes in range conditions in eastern Upper Michigan over the past 30 years have not influenced local mandibular morphology as reflected by the first two canonical variates. Regardless of general smallness of individuals, the mandibular morphology of the deer from the Cross Timbers area in Kansas appears to approximate more closely that of northern populations than that of the more southerly populations from Oklahoma and Texas.Sexual dimorphism on the first two canonical axes was observed.
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  • 59
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    Journal of Morphology 128 (1969), S. 195-227 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The mechanism of lung ventilation in chelonians has been much debated. Electromyographic studies show that the basic mechanism in the snapping turtle, Chelydra serpentina, is dependent on the activities of four major respiratory muscles that are capable of varying the volume of the visceral cavity. The precise mechanism utilized varies in response to environmental factors, especially the depth to which the animal is submerged. Chelydra tends to reduce muscular activity to a minimum, and hydrostatic pressure or gravity replaces muscular effort whenever possible. The response is subject to hysteresis. Both the mechanics and pattern of ventilation in Chelydra differ from those of Testudo. The differences appear to be attributable in part to Chelydra's markedly reduced plastron and more extensive respiratory musculature and in part to the different habitats occupied by the two species.
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  • 60
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    Journal of Morphology 128 (1969), S. 465-501 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The mechanisms of development of posterior levels of neural tubes of chick embryos were analyzed by study of serial cross-sections of a continuous series of normal embryos between 40 to 72 hours of incubation. Two extirpation experiments were performed in ovo on other embryos of the same stages. Descriptive studies revealed the presence of an overlap zone in which two types of neural tube formation occurred. Open neural tube formation (by fusion of neural folds) occurred dorsally in this region; closed neural tube formation (by canalization of solid medullary cord tissue) occurred ventrally. Extirpation of the posterior end of the neural plate produced defects within the lumbosacral region, indicating that the posterior neural plate participates in the formation of the lumbosacrum, and that the overlap zone is therefore in the lumbosacral region. Extirpation of the prospective neural tissue in the anterior end of the tail bud indicated that only the most posterior levels of the neural tube originate exclusively by cavitation of the tail bud. In both extirpation experiments a neural tube formed independently within the tail bud tissue, indicating that formation of the neural tube in this region is not dependent upon direct continuity with neural tissue anteriorly.
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    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The structure of the “Corneagen,” i.e., the epidermis lying beneath the cornea-lens of the lateral eyes of the adult intermolt Limulus polyphemus was studied with light and electron microscopy.This layer is composed of heavily columnar cells containing a striking number of cytoplasmic microtubules. Many of the microtubules are grouped into compact bundles or fascicles, generally each cell having at least one microtubule bundle. The cornealens end of each cell has numerous microvilli, each with a core of delicate filaments. The crypts between microvilli end in extracellular expansions and plaques of electron dense amorphous material are associated with these terminal expansions. Cytoplasmic microtubules appear to insert into these dense areas.The basal ends of the cells are thrown into many pseudopodial processes which extend into the surrounding extracellular space. The cytoplasm of the pseudopodia is composed largely of microtubules and their associated low density halos.Junctional complexes consisting of zonulae adhaerens and septate desmosomes are present between adjacent cells. Mitochondria, ER, cytoplasmic vesicles, Golgi stacks and other ultrastructural details of the epidermal cells are described. The ultrastructure of a column of pigment free processes lying between the apex of the lens cone and the underlying photoreceptive portion of the ommatidium is also described. Ducts or vessels of uncertain origin are present in the inter-ommatidial spaces.Possible roles played by the microtubules, the significance of their disposition and of their association with the dense subsurface plaques are discussed in terms of intracellular support, epidermis-lens attachment and extracellular pattern determination. In addition, the likelihood of the dense plaques being the site of microtubule assembly is considered.
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 129 (1969) 
    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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  • 63
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Drosophila melanogaster homozygous for the second chromosomal, recessive lethal gene 1(2)gl form puparia much later than wild type (+) and are unable to metamorphose. Implantation of + ring glands accelerates puparium formation by 1(2)gl hosts. The ring gland is a compound structure containing the prothoracic glands (pg), corpus allatum (ca), and corpus cardiacum (cc). An electron microscopic study demonstrates that in both the pg and ca the most common subcellular component is smooth surfaced endoplasmic reticulum (ser). In + flies the amount of ser per pg increases by ten times during the four hour prepupal period. In 1(2)gl flies which have spent two days in the prepupal period the pg looks juvenile and contains only 1% the amount of ser per cell found in the + prepupal pg. The ca cells look alike in both + and 1(2)gl individuals, and the cortical cells of the cc in both contain abundant neurosecretory spheres. We suggest that the + allele of 1(2)gl indirectly influences the synthesis of ser by the pg and that this is the site where dietary cholesterol is transformed to ecdysone.
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    Electronic Resource
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 129 (1969) 
    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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  • 65
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 129 (1969), S. 369-374 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Two embryos of Sphenodon punctatus, measuring 17.4 mm and 25.2 mm in length, were used in examining the arrangement of the septa and associated vessel pattern in the bulbus cordis. As in other reptiles, two septa subdivide most of the bulbus into three arterial vessels. The aortico-pulmonary septum passes through an angle of about 160° in its descent toward the ventricle. The aortic septum describes an angle of about 150°. Both partitions terminate anterior to the level of the ventricle, leaving an undivided remnant of the bulbus cordis from which the arterial vessels spring. When compared to other reptilian embryos whose bulbi have been studied in detail (i.e., Chrysemys and Aristelliger), Sphenodon shows similarities in the proximaldistal arrangement of the arterial apertures, the mode of descent of the bulbar septa, and the endocardial cushions, which comprise the bulbar septa. The rotation of the septa, however, is substantially different from that observed in the turtle and the lizard so far studied. The aortico-pulmonary and aortic septa in Sphenodon spiral through angles greater than those in Chrysemys and Aristelliger. This pattern in Sphenodon appears to represent a primitive phylogenetic feature in terms of the evolution of the bulbus in reptiles.
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  • 66
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Biochemical assay of acid phosphatase in normal and lens-regenerating eyes of the urodele Diemictylus viridescens, using p-nitrophenyl phosphate as substrate, demonstrates both soluble and lysosomal fractions of the enzyme. While the specific activity of the soluble fraction remains unchanged during lens regeneration, the lysosomal fraction shows four distinct rises in specific activity during the thirty-day regeneration period studied. These peak activities on the second, eighth, fifteenth, and twenty-second days post-lentectomy apparently correspond to lysosomal activity in the processes of wound healing, iris depigmentation, and lens differentiation which occur during urodele lens regeneration. On the basis of biochemical and histochemical studies as well as observations of morphological changes in the urodele eye as lens regeneration proceeds, it is postulated that there is a significant correlation between these morphological changes and the level and localization of the lysosomal acid hydrolases in the tissues in which the changes occur.
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