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  • 1975-1979  (3,091)
  • 1920-1924  (688)
  • Life and Medical Sciences  (3,779)
  • 1
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Specific (A-, B- and D-) granules as well as multivesicular bodies (MVB) with a dense core from the right and left atrium of a variety of mammals (mouse, rat, hamster, guinea pig, rabbit, young and old cat) were compared by quantitative ultrastructural and cytochemical methods as regards number, size, localization and reactivity. The number of specific granules was greater in the right atrium of the rat and lesser in the same atrium of the guinea pig. In the rat this difference was due to a greater number of all three types of specific granules in the right atrium. In the guinea pig, both A and B granules were more numerous in the left atrium. A greater number of granules was also found in the left atrium of hamster, rabbit and young and old cat but the difference with the right atrium was not significant. All atria contained the same type of specific granules but A- and B-granules were present in the left atrium not only in the paranuclear area, as in the right atrium, but also throughout the sarcoplasm. In both atria, all specific granules were argen-taphobic when stained according to the periodic acid-thiocarbohydrazide-silver proteinate technique of Thiery. They reacted positively to phosphotungstic acid-hydrochloric acid (PTA) (pH 0.3) as did the cell coat, residual bodies (Cgranules), lysosomes, Z-disks and a small portion of the Golgi complex. The PTA and PAS stains were abolished by acetylation, restored by saponification, unchanged by methylation and greatly diminished by sulfation. The MVB with a dense core, identical to those already noted in the cells of various endocrine glands, and thought to be crinophagic, were rare in the right atrium of all species and absent in that of the rat. They were much more numerous in the left atrium, particularly of hamsters, guinea pigs and cats and, to a lesser degree, of mice, rabbits and rats. They were silver negative. Their dense core reacted to PTA but their matrix, contrary to classical MVB without a dense core, did not.
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  • 2
    Electronic Resource
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 193 (1979), S. 71-97 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Detailed study has been made of the structure of the normal pulmonary artery of rat by both light (1-μ sections) and electron microscopy. After tying the pulmonary veins at the hilum, the lungs were fixed by simultaneous injection of glutaraldehyde into the pulmonary trunk and trachea. Study of distended arteries allows precise measurement and assessment of normal lung structure.Four regions of the pulmonary artery can be identified by wall structure and are described here-muscular, partially muscular, non-muscular and the newly described thick-walled oblique muscular. Electron microscopic examination has demonstrated in the non-muscular regions of the partially muscular arteries, an “intermediate” cell and in the non-muscular arteries, a pericyte. The intermediate cell lies internal to the single elastic lamina but external to the endothelial cell, is surrounded by its own basement membrane and contains filaments mainly along the adluminal region of the cell. The pericyte also lies internal to the single elastic lamina, is within the basement membrane of the adjacent endothelial cell and has previously been reported in the lung only in the walls of alveolar capillaries. The structure of the intermediate cell and its position suggest it is a transitional stage between the pericyte and smooth muscle cell.
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  • 3
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The activity of the electrolyte transport enzyme, sodium, potassium-activated adenosine triphosphatase (Na+,K+-ATPase), in the gills of the pinfish, Lagodon rhomboides, increased markedly following transfer of fish from brackish water to seawater. Cytochemical localization of Na+,K+-ATPase via its potassium-dependent phosphatase (K+-NPPase) activity in the branchial epithelium of pinfish adapted to seawater demonstrated that chloride cells are the major sites for the enzyme. Subcellularly, the heaviest depositions of reaction product were observed lining the cytoplasmic membrane surfaces of the labyrinth of anastomosing plasma membrane tubules that ramifies throughout the chloride cell cytoplasm. Enzyme activity was demonstrated also on the cytoplasmic surface of the apical crypt membrane and on the cytoplasmic surfaces of vesicles in the cytoplasm subjacent to the crypt. Deletion of potassium from the cytochemical incubation medium or inclusion of 10 mM ouabain abolished the reaction products associated with these membranes. The significance of these cytochemical results is discussed with reference to current hypotheses of chloride cell function.
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  • 4
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 193 (1979), S. 149-177 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 194 (1979), S. 247-255 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A new method for impregnation of biological specimens with thermosetting resins and elastomers is described. The method has the advantage that the original relief of the surface is retained.The impregnation is carried out by utilizing the difference between the high vapor tension of the intermedium (e.g., methylene chloride) and the low vapor tension of the solution to be polymerized. After impregnation, the specimen is subject to polymerization conditions without surrounding embedding material.The optical and mechanical properties can be selected by proper choice from various kinds of resins and different procedures, for example, by complete or incomplete impregnation. Acrylic resins, polyester resins, epoxy resins, poly-urethanes and silicone rubber have been found suitable for the method.Excellent results have been obtained using transparent silicone rubber since after treatment the specimens are still flexible and resilient, and have retained their natural appearance.
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  • 6
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The ultrastructure of the fetal rat anterior pituitary gland is described at term (day 22) and during experimentally prolonged gestation (days 23, 24, 25). The latter was achieved by daily subcutaneous injections of five mg progesterone to gravid females from the twentieth through the twenty-fourth day. Using morphological criteria for classifying pituitary cells (Moriarty, '73), six different types were observed: thyrotrophs, gonadotrophs, corticotrophs, mammotrophs, somatotrophs and non-granulated cells.During prolonged gestation (days 24 and 25 only), cells designated as cor-ticotrophs revealed changes suggesting increased activity, i.e., proliferation and dilation of the endoplasmic reticulum, dilated Golgi membranes and a reduction of secretory granules. In addition, meconium staining, which is indicative of fetal distress, was also observed on days 24 and 25. The ultrastructural changes noted suggest an increase in corticotroph activity due to fetal hypoglycemia and hypoxia which are known to occur as a result of placental insufficiency during prolonged gestation (Roux et al., '64; Vorherr, '75; Thliveris, '76).
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  • 7
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 194 (1979), S. 273-281 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: 3β-Hydroxysteroid dehydrogenase activity was localized in ovaries removed from rats during normal pseudopregnancy. Ovarian sections were incubated in media containing either pregnenolone (P-one) or dehydroepiandrosterone (DHA). P-one-3β-HSD activity appeared strongest on day 6 whereas DHA-3β-HSD was highest on day 13. NADH2 diaphorase activity was localized and observed to be greater than 3β-HSD.Both P-one- and DHA-3β-HSD activities were localized in primary-, secondary- and tertiary follicles; granulosa and theca interna cells have a variable potential for steroidogenesis. Mature tertiary follicles appear most responsive of the follicular population in steroidogenic potential. In atretic follicles, theca interna cells showed a marked ability for potential steroid production and may be one of the more stable sites of steroidogenesis. Interstitial tissue is a major site for potential estrogenic and progestational biosynthesis during the functional life of the ovary. Luteal cells exhibited strong ability for DHA-3β-HSD activity during the ongoing process of pseudopregnancy while P-one-3β-HSD activity declined in these cells as pseudopregnancy progressed. In summary, at the onset of pseudopregnancy, it appears that ovarian P-one-3β-HSD activity is greater than DHA-3β-HSD activity. Near the termination of this condition, DHA-3β-HSD activity is greater than P-one-3β-HSD activity in the rat.
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  • 8
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The effects of UVL-B and/or testosterone replacement therapy are compared in normal and castrated rats in order to determine whether testosterone is required for UVL-B (280-315 nm) stimulation of melanogenesis in the testosterone-dependent epidermal melanocyte system of the scrotal skin of black Long Evans rats. Testosterone is not a prerequisite for UVL-B stimulation of melanocytes as in both castrates and normal animals the melanocytes respond to UVL-B by increases in size, length and number of dendrites (dendriticness), and tyrosinase activity (intensity of Dopa reaction). Addition of testosterone to castrates does enhance the effects of UVL-B. However, UVL-B with or without testosterone cannot maintain normal melanogenesis in rats irradiated immediately after castration nor can it restore normal melanogenesis following long term castration. Both the amount of UVL energy/exposure and the number of exposures are important variables in stimulation of the epidermal melanocytes. Administration of a dose of UVL-B to castrates in a single exposure is ineffective, while the same overall dose spread over several exposures increases the size and dendriticness of melanocytes. Testosterone and UVL-B act synergistically in affecting melanogenesis although neither singly nor in combination are they able to fully restore normal melanogenesis.
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  • 9
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    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 194 (1979) 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 10
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 194 (1979), S. 201-211 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The present study is concerned with the fine structure of the myelin sheath in rat and monkey spinal roots. Pictures are obtained that show that the intraperiod gap of the myelin sheath is continuous and opens into both the internal and external mesaxons, which in turn open into the periaxonal and endoneurial extracellular spaces. These results are compatible with the idea that the intraperiod gap is a cleft that traverses the thickness of the myelin sheath and links the periaxonal and endoneurial extracellular spaces.
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  • 11
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    The @Anatomical Record 194 (1979), S. 213-232 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The present study extends earlier findings (Russell and Cler-mont, '76) by describing additional details of the structure, relationships, distribution, origin, and fate of tubulobulbar complexes. Freeze-fracture and thin section observations reveal few membrane associated particles and no appreciable cell coat in the membranes forming the tubulobulbar complex. The opposing plasma membranes of the complex do not appear to form a junction, although junctional formation might be expected by the close proximity (4.0 nm apart) of the Sertoli and spermatid plasma membranes. Sertoli filaments of the network which encircle the tubular portion of the complex measure 5.0-7.0 nm across and appear to insert into the Sertoli plasma membrane. Tubulobulbar complexes initially form in association with a cell surface modification (bristle-coated pit) of the Sertoli plasma membrane. The first tubulobulbar complexes develop large bulbous components (up to 2.5μm across), which soon lose connection with the spermatid and become incorporated into large phagocytic vacuoles (secondary lysosomes). As bulbs undergo dissolution, newly formed tubulobulbar complexes are observed to replace these structures. Thus, the data indicate that more than one generation of tubulobulbar complexes develop. Moreover, the tubular and bulbous portions of most dissociating complexes (as well as neighboring Sertoli lysosomes) show acid phosphatase activity. Near the time of sperm release, all complexes at the concave aspect of the spermatid head are resorbed. New tubulobulbar complexes, many lacking terminal bulbous dilations, form at the dorsal and lateral aspects of the spermatid head. These persist even after all ectoplasmic specializations and most Sertoli cytoplasm have been withdrawn from a position facing the spermatid head. The presence of tubulobulbar complexes just prior to the time of sperm release is in support of previous findings indicating that tubulobulbar complexes participate in anchoring the head of the late spermatid prior to sperm release. Past the zone of sperm release a few abnormally shaped cells, which had not been released with other spermatids of the same generation, display intact tubulo-bulbar complexes. The persistence of these and other structures may be the means by which abnormally shaped spermatids are retained and prevented from traversing the male duct system.
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  • 12
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    The @Anatomical Record 194 (1979), S. 267-272 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Ultrastructural screening of human breast tumor biopsies has revealed, in 43% of the carcinomas, and in 16% of the benign lesions examined, the presence of rod-like inclusions in mitochondria of epithelial cells. The inclusions are cylindrical in cross section, with a diameter of about 50 nm, and show regular striations in longitudinal sections. They are probably derived from cristae. Mitochondria with inclusions are usually enlarged and are found most frequently in epithelial cells of invasive tumors and near zones of tumor necrosis. Similar although not identical inclusions have been observed by other investigators in the liver of women with hydatidiform mole or choriocarcinoma, of pregnant women, and of women taking oral contraceptives. Identical inclusions have been found in mitochondria of HeLa cells treated with anti-HeLa serum. Although no clear-cut correlations were found between the finding of inclusions and parameters such as age of patients, nuclear grade or lymphocytic infiltration of the breast tumors, it is conceivable that the presence of mitochondrial inclusions reflects the effect of hormonal or of immunological factors.
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  • 13
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    The @Anatomical Record 194 (1979), S. 283-291 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Alkaline phosphatase (ALK Pase) activity can be detected histochemically in the taste buds of rats but not mice. Since taste buds develop, regenerate and are maintained under the influence(s) of the sensory nerve it was decided to study cross-species regenerated buds of these two animals to determine whether the nerve also regulated ALK Pase development in taste cells. Grafts of rat sensory ganglion and mouse tongue or mouse ganglion and rat tongue were combined in the anterior chamber of the eyes of immunologically-deficient nude mice and the cross-species buds that developed at 35 days were examined histochemically for ALK Pase. The results revealed that the rat nerve did not cause ALK Pase to appear in any buds found in mouse tongue grafts and that mouse nerve could support buds containing ALK Pase in rat tongue tissue. Because the cross-species regenerated buds were histochemically characteristic of those normally found in rat or mouse tongue, there is no evidence that the foreign nerve altered gene expression for ALK Pase in the target organ, and the action of the nerve on gustatory epithelium appears to be that of activation and maintenance.
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  • 14
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 194 (1979) 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 15
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    The @Anatomical Record 195 (1979), S. 31-45 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The development of granulocytic hemopoiesis in the fatty marrow of metatarsal bones and caudal vertebrae of adult mice was studied in histological sections for up to six weeks following subcutaneous innoculation of granulocytosis inducing mammary carcinoma. The initial events observed were increase and engorgement of fatty marrow sinusoidal vascular beds, accompanied by numerous lymphoid mononuclear cells in the sinusoids and in the stroma. Foci of granulocytopoiesis appeared admixed with lymphoid cells in the stroma and near the endosteum. Hyperplastic granulocytopoiesis eventually predominated in the marrow of these bones as well as the femoral and sternal marrow of tumor bearing mice. The morphological findings suggested the possibility of stem cell and progenitor cell migration into fatty marrow, but activation of dormant stem cells could not be ruled out. The prevalence of granulocytopoiesis in the entire skeletal marrow in tumor bearing mice may seriously impair the production of other cellular components of the marrow including lymphocytes, reduced production of the latter would imply serious compromise for the immune system of the tumor bearing animals.
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  • 16
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 195 (1979), S. 115-242 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 17
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 195 (1979), S. 301-309 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Ciliated cells surrounded by mucous cells were found near the base of the peripapillary trench of the rat circumvallate papilla. The ciliated cells occurred singly or in small groups. Each cilium showed the nine plus two filament pattern characteristic of motile cilia.We consider that these cells function in wetting the taste pores, circulating saliva containingtastants and removal of debris from the papillary trench.
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  • 18
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Lymphocyte production by mesenteric lymph nodes of normal young pigs was studied by intranodal injections of either tritiated thymidine or tritiated deoxycytidine as DNA precursors. One or two days after selective labeling of the mesenteric lymph nodes the relative and absolute number of lymphocytes derived from mesenteric lymph nodes were determined autoradiographically in the following organs: mesenteric, cervical and inguinal lymph nodes, spleen, thymus, bone marrow, peyer'spatches, tonsil, different regions of the gut, lung and liver. The overall cell production of mesenteric lymph nodes, as derived from the sum of all labeled cells one day after labeling, was estimated to be about 7 × 109 lymphocytes. Up to 40% of all newly formed lymphocytes had already left the lymph nodes within one day and were found in all organs studied. There was a preferential homing to the mucosa of the small intestine, but a considerable number migratedto the spleen and even to the thymus and bone marrow. In lymphoid organs all labeled cells were small and medium-sized lymphocytes one and two days after labeling. In cervical lymph nodes, spleen, tonsil and peyer's patches the relative distribution to T and B cell areas was determined. There was an obvious preference of newly formed lymph node cells to home to T cell areas. The differences of labeling between thymidine or deoxycytidine were surprisingly low.
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  • 19
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    The @Anatomical Record 195 (1979), S. 63-72 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The differentiation of mammalian white adipocytes from prenatal through early postnatal periods was studied by light and electron microscopy in C57BL mice. Anatomical regions chosen for this study were the epididymal, mesometrial, mesenteric and inguinal fat pads. In each of these regions, adipocytes differentiated from fibroblast-like cells (preadipocytes) characterized by an ovoid nucleus, profiles of rough endoplasmic reticulum, microtubules, microfilaments, spherical mitochondria, and small multiple lipid inclusions. Preadipocytes of the inguinal fat pad were first observed prior to birth (17-19 days), whereas, in the other anatomical sites, these cells were not observed until one to three days postnatally. As differentiation proceeded, and as the adipocytes assumed a spherical shape, there was a progressive decrease in the amount of rough endoplasmic reticulum and microfilaments concomitant with transient glycogen storage and an increase in the size of lipid droplets. Mature unilocular adipocytes were observed in the inguinal fat pads at three days of age. On the other hand, these cells did not appear until seven days after birth in the epididymal fat pad, mesometrium and mesentery. Regardless of the anatomical region studied, the differentiation of preadipocytes to adipocytes proceeded similarly. Preadipocytes could not be distinguished from fibroblasts morphologically within the fat depots studied. Adipocytes at the mid-stages of differentiation and in all regions studied occasionally exhibited close intercellular contacts of varying morphology.
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  • 20
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    The @Anatomical Record 195 (1979), S. 109-113 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Epiphyseal growth plate chondrocyte nuclei of growing rats were studied for histone content using the ammoniacal silver technique. This stain, which is specific for the demonstration of the arginine-rich fractions of histones, revealed that growth plate nuclei vary in their histone content. Nuclei of cells of the proliferating zone revealed a significantly greater amount of postformalin ammoniacal silver deposit consistent with the presence of arginine-rich histones.
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  • 21
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    The @Anatomical Record 195 (1979), S. 73-93 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Cell junctions between endothelial cells and between connective tissue cells (leptomeninges) of the rat choroid plexus were studied by freeze-fracture. Special attention was paid to the problems of identifying fractured cell membranes and fracture faces. Tight junctions in arterioles are comprised of continuous small-meshed networks of strands appearing as shallow grooves with aligned particles on E-faces, and low ridges with some particles on P-faces. In the fenestrated capillaries the tight junctions are represented by discontinuous, isolated slightly elevated ridges with some particles on P-faces, and corresponding shallow grooves devoid of particles on E-faces. Junctions in venules appeared as a less developed version of the junctions in the fenestrated capillaries. Extended areas of the meningeal cell membranes exhibit cell junctions. Tight junctions in this tissue are comprised of a loose discontinuous arrangement of isolated, often branched junctional elements. On P-faces the elements appear as elongated crests with a distinct furrow running along the edge of the crest, occupied by a few particles. On E-faces corresponding elongated impressions are present and occupied by aligned particles and a few short bars. The arrangement of these tight junction elements are not supportive of any significant barrier function. Small gap junctions occur “freely” in the membrane, or they are sometimes surrounded by tight junction elements. Very large gap junctions (up to about 10,000 particles) are mostly surrounded and interconnected by tight junctional elements. The possible significance of the variability of gap junction size, and the relation to tight junction elements is discussed.
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  • 22
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    The @Anatomical Record 195 (1979), S. 95-107 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: During eruption of the mouse incisor part of the periodontal ligament moves along with the tooth in occlusal direction and is degraded in the gingiva, just apically of the junctional epithelium. When studied with the electron microscope some connective tissue cells (fibroblasts) showed disorganization of both nucleus and cytoplasm. In other cells vacuoles were observed containing partly degraded cellular constituents. Sometimes within these vacuoles electron dense material with the appearance of clumped chromatin was observed. On the basis of this observation it is concluded that heterophagocytosis contributes to the process of fibroblast breakdown. The ultrastructure of these heterophagic cells resembled that of fibroblasts.Collagenous fibrils were observed within cytoplasmic vacuoles of fibroblasts indicating that collagen is phagocytosed and probably digested in the lysosomal apparatus. Part of the intercellularspace was filled with a homogeneous material of moderate electron density, intermingled with some collagenous fibrils.Within some cells of the junctional epithelium partly degraded material was observed which may indicate that the epithelium contributes to the removal of residual products of connective tissue degradation.
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  • 23
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    The @Anatomical Record 195 (1979), S. 257-264 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The study describes a stereological method for detecting relative changes in cells-with respect to their average volumes and to their frequencies within one cm3 of exocrine cells. The method is based on surface area ratios (Bolender, '1979) and can detect changes comparable to those obtained with the numerical density approaches (Loud, '68; Weibel et al., '69; Bolender, '74; Williams, '77). The new method requires only intersection counts- the same ones that are used for surface density estimates- and, as a result, avoids the difficult and often problematic procedures of the numerical densities. In analyzing the cellular changes in vitro, the choice of either a zero or timed control was found to exert a major influence on the results. Timed controls were required to “isolate” the experimentally induced changes from those Produced by the incubation medium.
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  • 24
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    The @Anatomical Record 194 (1979), S. 539-545 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A cylinder of gelatin containing silver spongy granules was placed in and lay within the masseter muscle, the periosteum, and the mandible, and terminated in the medial pterygoid muscle of young (3 month-old) growing miniature pigs.On the basis of an animal sacrificed one week after placement of the cylinder, it was found that the suspending gelatin was removed by cellular activity. Nine months later the remaining animals were sacrificed. Periodic X-rays were taken during the course of the experiment. After sacrifice, the mandible and associated tissues were histologically examined. The results of this study suggest that the silver granules in the muscles maintained their location during growth; the silver granules in the mandible moved forward with mandibular growth. “Slippage” appeared to occur external to the fibrous layer of the periosteum; the site of movement was revealed by the trail of the silver granules. The described method should prove of value in studying the growth interrelationships between bone, periosteum, and muscle.
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  • 25
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Electron microscopic observations and measurements were made on thin-sectioned chromatin fibers and fibrils obtained from nuclei of mature chicken erythrocytes. The nuclei were isolated in low ionic strength gum arabic and octanol then extracted sequentially with (1) 0.14M NaCl, (2) 0.25 N HCl, (3) buffer saturated phenol, (4) hot 5% SDS and 0.14 M 2-mercapto-ethanol and, (5) 0.4 N NaOH. The amount of nuclear protein removed at each of the first four extraction steps was 1, 86, 3 and 11% of the total, respectively. Each extract was characterized by electrophoretic profiles. At each extraction the chromatin was fixed by adding large quantities of a mixture of equal volumes of sodium cacodylate buffered 8% (w/v) glutaraldehyde (pH 6.8) and 2% OsO4 (w/v), directly into (1) an aliquot of the chromatin in extraction fluid, and (2) an aliquot of the chromatin after water washing and swelling. Three size classes of chromatin structure were seen in thin sections prepared for high resolution transmission electron microscopy and stained with uranyl acetate and lead citrate. A thick fiber of about 25 + nm diameter was the predominant large fiber seen in freshly isolated nuclei or in nuclei after salt extraction. This 25 + nm fiber has a substructure consisting of 3.2-5.2 nm diameter fibrils. After water swelling of such freshly isolated or salt extracted nuclei a fiber of about 10 nm diameter was the predominant large fiber instead of the 25 nm diameter fiber. The HCl extraction step which is known to remove histones, caused the disappearance of both the 25 nm and the 10 nm fibers. High magnification (600,000 × ) micrographs of the chromatin at all procedural steps, except the last NaOH step, reveal the fibril to be omnipresent. This fibril tends to decrease somewhat in diameter during the protein extraction steps to a 2.5 nm diameter fibril after the hot SDS extraction. A fibril of 2.5 nm diameter is expected of naked double helical DNA stained with a positive stain. The NaOH, which is known to denature DNA, completely destroyed the remaining fibril. We interpret our results to indicate that the larger chromatin fiber seen in micrographs of thin-sectioned chromatin has a fibrillar substructure which probably represents a double coil of native DNA which may have a thin protein coating of its own. The latter fibril may in turn be wrapped around a hydrophobic histone domain, perhaps reflected in the 10 nm diameter fiber which is seen upon swelling of the chromatin. This 10 nm diameter fiber is thought to be further packaged by folding into the 25 + nm diameter chromatin fiber most frequently reported in thin sections of eukaryotic cell nuclei in situ.
    Additional Material: 24 Ill.
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  • 26
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: High incidences of cleft lip and palate (CLP) Produced by maternal intraperitoneal administration of 75 mg/kg pehnytoin on gestational day 10 to A/J mice are associated with asevere size reduction in the lateral nasal process. Scanning and transmission EM analyses of this region demonstrate a marked change in the morphology of the mesenchymal cells underlying the surface epithelium in treated versus control day 11 (7-tail somite) embryos: long, branching cellular processes, which form a dense meshwork that appears to interact with the epithelial basement lamina in control embryos are undeveloped or absent in phenytoin-treated embryos. The ultrastructural morphology of these cell processes is described and their possible importance in normal development is discussed. Scanning EM observations of incomplete clefts of the lip which frequently result from phenytoin treatment indicate that Simonart's bands form from fusionof the lateral and medial nasal processes in association with a lack of fusion of the maxillary process with the medial nasal process.
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  • 27
    Electronic Resource
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 195 (1979), S. 311-316 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Unilateral ovariectomy (ULO) was carried out on rats at Day 8 of gestation: term is Day 23. The effect on peripheral plasma progesterone levels at Day 16 and on growth and cellular changes in the remaining corpora lutea (CL) at Day 17 was determined by comparison with results from control and sham-operated rats. ULO increased the volume of remaining CL by 18% at Day 17. At Day 16 this effect was only apparent in rats with three or fewer CL remaining. CL hypertrophy was due to an increase in the volume of individual luteal cells and not to cell hyperplasia. Luteal cell nuclear volume also increased as did the number of endothelial cells per corpus luteum. The proportion of the corpus luteum occupied by vascular space did not alter.ULO had little effect on mean plasma progesterone levels at Day 16 (92 ± 7 ng/mltreated; 86 ± 11 ng/ml controls). In rats with three or fewer CL remaining, however, progeserone levels were low (51 ± 7 ng/ml).It was concluded that ULO can enhance the growth of corpora lutea and perhaps increase their rate of progesterone production.
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  • 28
    Electronic Resource
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 195 (1979), S. 357-374 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The morphogenetic events associated with rabbit eggs aged in vitro for 12 to 50 hours prior to mixing with sperm have been examined by light and electron microscopy. After 12 hours in culture, morphological alterations of the meiotic spindle and the cortex of unfertilized eggs were evident. By 24 to 50 hours in culture, unfertilized eggs contained subnuclei, structures which formed when individual and/or groups of meiotic chromosomes dispersed and became invested by a double-laminated structure reminiscent of a nuclear envelope.Although most eggs obtained 11.5 to 12 hours after induced ovulation and in vitro fertilized displayed morphogenetic patterns similar to those described for in vivo fertilized ova, some (10%) contained three pronuclei. Many eggs obtained 13 to 15 hours after induced ovulation and subsequently mixed with sperm in vitro appeared to undergo processes of fertilization typical of in vivo fertilized eggs, however, approximately 30% contained subnuclei in association with the male pronucleus. Few eggs (15%) aged 12 hours prior to in vitro fertilization displayed patterns of pronuclear development and association typical of fertilized unaged ova. Subnuclei developed in many of the fertilized ova. Supernumerary sperm nuclei, which did not develop into male pronuclei, were observed in some zygotes. Cleavage of eggs aged 12 hours prior to fertilization was abnormal or retarded. After 24 hours in culture approximately 16% of the eggs fertilized. Seventy percent of the fertilized eggs failed to Support the development of a male or female pronucleus.
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  • 29
    Electronic Resource
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 195 (1979), S. 375-386 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: “Uncouplers” of oxidative phosphorylation (sodium azide, DNP, and oligomycin) alter the location of microtubules within murine mast cells. Both cytoplasmic microtubuless, perpendicular to the plasma membrane within cell surface folds, and intranuclear microtubules wereobserved. In addition, one or more dense plaque-like structures adjacent the plasma membrane in mast cells appeared following incubation in the antimetabolities. Intranuclear microtubules and cytoplasmic microtubules within the cell surface ridges disappeared in azide-treated mast cells that were reincubated or “recovered” in PBS. However, both these structures remained in oligomycin- and DNP-treated murine mast cells following reincubation.
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  • 30
    Electronic Resource
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 195 (1979), S. 397-412 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Structural correlates of milk lipid absorption and chylomicron production were studied in 10-day-old suckled rats. The gastric and duodenal contents and duodenal mucosae were examined with the light and electron microscopes. In the gastric lumen the milk lipid globule cores were smooth, circular and uniformly electron opaque. Many membranes and lamellar structures with a trilaminar and multilamellar appearance were adherent to the peripheries of the cores. In the central duodenal lumen the milk lipid globule cores were also smooth, circular and uniformly electron opaque. Very few milk lipid globules in the duodenal lumen showed adherent membranes or lamellae. Membrane fragments and lamellae were present in the lumen separate from the milk lipid globules. In the duodenal lumen between villi the milk lipid globules had multiple electron lucent indentations of the core. It is believed that the irregular peripheries of the milk lipid globule cores are the result of lipolysis within the duodenal lumen acting at the milk lipid globule surface. This lipolysis of triacylglycerol would produce amphiphilic lipids which may result in the electron lucent spaces at the milk lipid globule periphery. The absorptive epithelial cells along the length of the duodenal villus varied in structure relative to their position at the tip, middle, or base of the villus. Typical mid-villus epithelial cells contained lipid droplets averaging 0.3-μm diameter in the smooth and rough endoplasmic reticulum and in Golgi complexes in the apical cytoplasm. Villus tip and villus base cells contained large lipid droplets between 7-16 μm. Only a few 0.3-μm lipid droplets were present within these cells. These large lipid droplets appeared to be accumulations of triacylglycerol present in the apical cytoplasm associated with lamellar and membranous structures. Numerous chylomicrons were present between epithelial cells located in the middle region of the villus while significantly fewer chylomicrons were seen between epithelial cells at the tip and base of the villus. These observations suggest that the cells at the middle of the duodenal villus of suckling rats were more efficient in the production of chylomicron triacylglycerol derived from incoming milk triacylglycerol than cells at the tip and base of the villus.
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  • 31
    Electronic Resource
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 193 (1979), S. 823-830 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The cellular pattern of corpus luteal (CL) growth was studied in rats at Days 6, 10, 12, 14, 16, 17 and 22 of pregnancy: term is Day 23. Measurements were taken of the percentage of the CL occupied by luteal cells, connective tissue and vascular space, luteal cell and nuclear volumes, and the number of luteal and endothelial cells in each of three CL in both ovaries of five rats at each stage of pregnancy. Total CL volume increased from 1.08-3.23 μl over Days 10-17. This was mainly due to an increase in luteal cell volume from 3.72 pl to 9.30 pl. Neither the number of luteal cells per CL (range 212,000-287,000) nor the percentage of the CL occupied by luteal cells (range 85-90%) had much influence on growth. Nuclear volume increased roughly in proportion to cytoplasmic volume but near term it decreased despite little change in cytoplasmic volume. The number of endothelial cells per CL increased steadily from 398,000 at Day 6 to 1,545,000 at Day 22. There was a strong negative correlation (r = -0.78) between the number of luteal cells per CL and mean luteal cell volume that was evident at all stages of pregnancy. There was a positive, but weaker correlation (r = 0.35) between number of luteal cells and CL volume. Thus, CL volume seems to be partly determined by the number of luteal cells at Day 6 but this effect is moderated by local control of luteal cell volume.
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  • 32
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 193 (1979), S. 831-855 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Various stages of embryonic human secondary palatal development were examined for the presence of epithelial glycogen. Utilizing periodic acid-Schiff's reagent staining of thich plastic sections and osmium ferrocyanide enhancement of thin sections, dramatic changes in epithelial glycogen distribution were noted during palatogenesis. Prior to fusion, the epithelium destined to adhere in the midline exhibited a marked diminution of glycogen in the superficial cell layer. This cell layer was composed of slender dense cells and cuboidal cells undergoing lysis. Adjacent nonfusing epithelium was markedly different and contained large glycogen reserves in its superficial cell layer. Glycogen may play a role either as precursor for specific adhesive macromolecules or as a physical agent capable under the influence of appropriate enzymes of causing cell lysis.
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  • 33
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 193 (1979), S. 857-861 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A procedure for studying small biological specimens with the SEM, using frozen sections of fixed material is described. Controlled fixation schedules and convenient handling of sections insure optimal preservation of cell shape and size. The greatest advantage of the method presented is to allow scanning through any desired plane of the specimen, even in those planes parallel to an epithelial face. SEM of frozen sections is thus helpful for the study of cell distribution and organization within a tissue.
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  • 34
    Electronic Resource
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 193 (1979), S. 863-881 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Destruction of mouse oocytes in primordial and small primary follicles in response to treatment with 3-methylcholanthrene (MC) was studied at the ultrastructural level. Four-week old C57Bl/6N (B6) strain mice received a single injection of 80 mg/Kg MC in corn oil intraperitoneally. Controls received only corn oil. Ovaries from animals were prepared for light and electron microscopic examination at specified intervals after treatment. The number of primordial follicles remained constant in control animals. In contrast, their number decreased significantly (P 〈 0.01) by three days, and they were depleted by seven days after MC treatment. Subtle degenerative modifications were noted in the ooplasm of primordial follicles two days after treatment. These changes consisted of vesiculation of mitochondrial cristae, increased electron density of the mitochondrial matrix, myelin structures in lipid droplets and in mitochondria. More advanced stages of degeneration of primordial follicles were characterized by further vesiculation or disappearance of mitochondrial cristae, chromatin clumping, and increased density of the ooplasm. Small primary follicles had undergone similar initial degeneration as primordial follicles. In more advanced stages of degeneration nuclear and cytoplasmic contents condensed, endoplasmic reticulum, Golgi complex and mitochondria swelled, small vesicles and multivesicular bodies appeared. In the most advanced stages of degeneration of small primary follicles it appeared that small portions of the oocyte were engulfed by the surrounding follicular cells. It is concluded that exposure of B6 mice to a single dose of MC results in atresia of oocytes in primordial and small primary follicles. Ultrastructurally, these degenerating oocytes of treated mice looked much like the spontaneously atretic oocytes in untreated animals.
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  • 35
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The wheat germ agglutinin-gold labeled ovomucoid (WGA-Ovo-G) method has been employed in the ultrastructural localization of WGA surface receptor sites on gluteraldehyde-fixed normal human and guinea pig bone marrow cells. The number of gold particles per micron of cell surface were counted and data subjected to statistical analysis. WGA labeling ofthe bone marrow cells was found to be quite heavy and evenly distributed along the cell surface. Only macrophages, in both species, and a number of lymphocytes in the guinea pig exhibited limited WGA labeling. Comparison of morphologically similar cell types in human and guinea pig marrow indicated that WGA receptor sites were more abundant on the guinea pig hemic cells. WGA surface labeling was found to be not only related to cell type and to animal species but, in some instances, varied with the stage of maturation of a given cell line; viz., neutrophilic cell series in both man and guinea pig and erythrocytic cell series in the guinea pig.
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  • 36
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The morphology of the human atrioventricular node, atrioventricular bundle and bundle branches is described. A block of tissue bounded by the ostium of the coronary sinus, the pars membranacea, the septal leaflet of the tricuspid valve and the atrial and ventricular septa is removed. This block is then sectioned serially from the right endocardial surface in the frontal plane of the heart. Sectioning in this way produces fewer sections than from techniques previously described. Outlines of the atrioventricular node, atrioventricular bundle and proximal bundle branches are digitally registered and stored in a computer. Three dimensional reconstructions of the structures are then generated by computer and displayed on an oscilloscope so that the entire three dimensional image can be rotated in any plane. Stereoscopic image pairs are produced to assist perception of the shape of the atrioventricular node, bundle and branching patterns of the bundles. This technique is unique in that it describes a method from which a relatively small number of histologic sectionsare generated permitting not only a complete histologic examination, but also a study of the morphology of the area.
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  • 37
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: This study presents scanning electron microscopic (SEM) observations of topographicalchanges that occur during morphogenesis of rod cells in the albino rat. Correlative transmission electron microscopy (TEM) was also utilized. Albino rats ranging in age from birth to three weeks were used for the study. Tissues were prepared by conventional methods for SEM and TEM.At birth, numerous irregularly arranged inner segments extend from the external surface of the sensory retina. They are spherical, smooth surfaced and possess a randomly oriented cilium. The internal morphology of these immature inner segments is comparable to that observed in other vertebrate species. Statistical analysis reveals a rapid increase in the number of rod cells during the first week. This period is characterized by the elongation of inner segments and their associated cilia. Microvilli project from the apices of Müller cells, but not from adjacent inner segments.By day 5, cilia occasionally display small bulbous outer segments. They are more numerous by day 8 and are usually eccentrically positioned at the tips of cilia. By day 11, outer segments are abundant and frequently obscure from view the underlying inner segments and associated cilia. Elongated cylindrical outer segments are present within the posterior retina at the end of the second week. However, rod cell morphogenesis lags in the peripheral retina. Topographical variations between developing photoreceptor cells in mammalian and non-mammalian retinas are discussed.
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  • 38
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Tail bud formation was studied in chick embryos by light and electron microscopy. The caudal part of the neural groove at stage 11 is flanked by widely separated neural folds and merges posteriorly with the shallow primitive groove. The neural groove and primitive streak partially overlap. The depth of the neural groove gradually decreases antero-posteriorly within this overlap zone while the dorso-ventral thickness of the streak progressively increases. The anterior end of the streak begins to form a spherical accumulation of mesenchymal cells, the incipient tail bud, concomitant with closure of the posterior neuropore. Formation of the posterior body fold results in consolidation of the remainder of the streak into the definitive tail bud. The overlap zone between neural groove and primitive streak is retained as the tail bud forms. Thus the posterior end of the neural tube and anterior end of the tail bud overlap. The latter undergoes cavitation to form the ventral part of the spinal cord within this overlap region.The tail bud is initially continuous with an overlying, flattened layer of ectoderm and an underlying, columnar layer of endoderm. A bilaminar ectodermal epithelium forms directly above the developing neural tube as the dorsal portion of the tail bud undergoes cavitation. Most of the endodermal cells are displaced from the ventral surface of the tail bud by the posterior body fold and condensed into a disk-shaped region which ultimately gives rise to tail gut.
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  • 39
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 193 (1979) 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 40
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: 3H-concanavalin A and the concanavalin A-horseradish peroxidase staining technique were used to study the distribution of surface coat material on the epithelium of the nasal folds and nasal groove of mouse embryos. In stages shortly before and during epithelial fusion concanavalan A stained or labeled material was present at apical surfaces of epithelial cells of the nasal groove and nasal folds. Silver grains, representing bound 3H-concanavalin A, were counted in defined areas of the nasal groove and presumptive fusion area in both anterior and posterior regions of the nasal folds. For both stages examined there was a significant increase in the amount of 3H-concanavalin A bound by presumptive fusion areas in posterior regions of the nasal folds as compared with anterior regions; i.e., the amount of surface coat was greater in the region just prior to the point of contact between the nasal folds. This finding is consistent with results from investigations of palatal shelf and neural fold fusion which suggest that increased synthesis of surface coat material is associated with adhesion and fusion of epithelial folds and shelves.
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  • 41
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 193 (1979), S. 197-211 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Development of the rete ovarii and its contribution to the cells of the ovary were examined in fetal rats. Histochemical and autoradiographic techniques were used for the observations between days 15 and 21 of gestation. The data presented indicate that the rete system contributes somatic cells to the ovary before birth.The basement membrane which surrounds the cuboidal epithelium of the mesonephric tubules immediately adjacent to the ovary becomes discontinuous on day 15 of gestation. The mesonephric epithelial cells in this region form a knot or clump of pleiomorphic cells, with no apparent tubular organization, and this clump later becomes surrounded by a basement membrane. On day 17 of gestation the newly established fetal rete ovarii is comprised of three regions; (1) the extraovarian mesonephric tubules (ER), (2) intraovarian cords of flattened epithelioid cells which surround the oogonia (IR), and (3) a knot or clump of cells connecting the ER and IR regions (CR). The entire rete system is enclosed by a continuous basement membrane as defined by Periodic Acid-Schiff Reagent techniques.Autoradiographic and quantitative analyses demonstrate that the ER tubule cells proliferate and are incorporated into the other regions of the rete system. These processes begin on day 17 and continue until at least day 21 of gestation. The role these mesonephric tubule cells may play in the regulation of meiosis and their early contribution to the presumptive granulosa cell population is discussed.
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  • 42
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 194 (1979), S. 293-309 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A combined ultrastructural and biochemical study of the avian oxynticopeptic cell was performed. Scanning electron microscopy demonstrates that this cell undergoes great changes in the shape of its apical pole in relation to secretory activity. These changes are confirmed by transmission electron microscopy and by freeze-fracture images. The biochemical finding of actin- and myosin-like proteins in high-speed supernatants of homogenates of these cells as well as the ultrastructural and cytochemical localization of actin-like filaments in their apical poles suggest a possible participation of these proteins in the above-mentioned changes. Thus, the study of cytoplasmic matrix elements and of their organization may be highly relevant in the search for a correlation between structure and function in these cells.
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  • 43
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    The @Anatomical Record 194 (1979), S. 311-323 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Osteoclastic bone resorption was studied using 45Ca-labeled fetal rat bones cultured in the presence of parathyroid hormone (PTH) and an anti-invasion factor (AIF) derived from bovine hyaline cartilage which is enriched in a collagenase inhibitor. The specific morphological expressions of osteoclasts cultured in PTH and AIF were observed in both light and electron microscopy and analyzed cytometrically. Stimulation of bone resorption with PTH revealed significant increases in the numbers and activity of osteoclasts, whereas bones cultured in the presence of AIF showed significant decreases in numbers of osteoclasts and altered cell features including the loss of osteoclast contact with bone surfaces. These structural modifications were evaluated with 45Ca release data derived from matched-pair explants of fetal rat bones, revealing the existence of a relationship between resorptive states of the cultured bones and morphological expressions of osteoclastic activity.
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  • 44
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    The @Anatomical Record 194 (1979), S. 325-353 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The choroid plexus of mature and old rats has been examined by both scanning and transmission electron microscopy. It has been shown that the macrophages lying upon the ventricular surface of the choroid plexus have a close association with burr-like protrusions that extend from the apical surfaces of the choroidal epithelial cells. These protrusions have a dark cytoplasm filled with vesicles and tubules, and projecting from them are thin, shrunken microvilli. It is suggested that these protrusions are phagocytosed by the macrophages and that they are the source of some of the inclusions which become increasingly common within the cytoplasm of macrophages in older rats. The lateral surfaces of the choroidal epithelial cells have also been examined in the scanning electron microscope after exposure of the surfaces by dissection. In such preparations it is apparent that the elaborate interdigitations between adjacent cells are effected by irregular and vertically arranged folds confined to the basal portions of the lateral cell surfaces. Lastly, it has been shown that at the junction between the choroid plexus and the ependyma in the lateral ventricle, there are two modes of transition between the choroidal and ependymal epithelia. In one, typical choroidal and ependymal epithelial cells lie next to each other to produce a distinct and continuous boundary. In the other mode the boundary is also continuous, but there are modified ependymal cells present. These modified cells have short, relatively sparsely distributed microvilli and not more than one or two cilia.
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  • 45
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    The @Anatomical Record 194 (1979), S. 389-403 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: In order to demonstrate features of the cerebrospinal fluid (CSF) path in the amphibian, 2-6 m̈l of either Evans Blue-albumin (EBA) or ferrocyanide were injected into the ventricular system of anesthetized bullfrogs. The animals were sacrificed 1 to 135 minutes after injection by either quick freezing (EBA injections) or fixative perfusion (ferrocyanide injections). The contents of the cranial and vertebral cavities were then examined grossly and histologically for distribution of the tracers. In all animals, the tracers were seen throughout the ventricular cavity and in the subarachnoid space surrounding the caudal hindbrain. The site of communication between these two fluid spaces was the posterior tela of the hindbrain. Within this tela, “pores” were found between groups of pavement-like ependymal cells. In many animals, tracer was also observed in the vertebral subarachnoid and epidural spaces, adjacent to spinal nerve roots. In three EBA-injected animals, this tracer was also seen in the subcardinal lymph spaces. These findings suggest that the subarachnoid space in the bullfrog communicates functionally with the ventricular system by way of specialized “pores” in the posterior tela of the hind-brain. There is also indication of movement of fluid within the subarachnoid space which is predominately caudal in direction, with a primary absorptive path for CSF that consists of a perineural route to the lymphatic system.
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  • 46
    Electronic Resource
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 193 (1979), S. 257-267 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A highly specific serotonin binding protein (SBP) has been found in serotonergic neurons in both brain and gut. This protein has an extremely high affinity for serotonin and may be a storage protein. Serotonin is found in many endocrine cells, including parafollicular cells of the sheep thyroid, as well as in neurons. SBP is also present in sheep thyroid. The present study was done to localize the protein in the gland. Thyroid glands were divided into five segments. Concentrations of serotonin and SBP, as well as parafollicular cell volume were measured in each. Serotonin was assayed by enzymatic conversion to melatonin using tritiated S-adenosylmethionine. SBP was assayed by molecular sieve chromatography on sephadex G-50. The relative volume of parafollicular cells was obtained by stereological analysis of electron micrographs. Experiments were also done to demonstrate these cells by histofluorescence and radioautography following incubation with tritiated 5-hydroxytryptophan. Good correlations were found between serotonin and SBP concentrations, and parafollicular cell volume. These peaked in the rostro-central portion of the gland and were minimal at the poles. We conclude that thyroid SBP is probably localized in parafollicular cells.
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  • 47
    Electronic Resource
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 193 (1979), S. 269-291 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Light and electron microscope studies of the woodchuck anal scent gland revealed that it is composed of apocrine and sebaceous components emptying into a common duct. In the apocrine acini, the single secretory cell type showed evidence of both merocrine and apocrine secretion. Merocrine secretion resulted in the release of the contents of apical secretory granules while apocrine secretion released apical caps of cytoplasm by a process involving the following: (1) formation of an apical cap, usually containing no organelles or secretory granules; (2) appearance of a single row of flattened vesicles forming an incomplete barrier between the apical cap and the remaining cell cytoplasm; and (3) fusion between vesicles and plasmalemma, causing progressive constriction of the neck of the apical cap and eventual cap release. Since both merocrine and apocrine secretory processes have been reported in three other types of apocrine glands, it is likely that the occurrence of both processes in a single cell is a general characteristic of apocrine cells.Several features apparently unique to these particular apocrine cells were observed, including secretory granules of a single morphological type and a population of small dense-cored basal vesicles of unknown function. Therefore, it would appear that, just as with merocrine cells, apocrine cells from different types of glands also have distinctive morphologies which probably reflect real differences in their functions and products.
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  • 48
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 194 (1979), S. 477-489 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Injury in the periphery of the lung was studied in rats given intratracheal trypsin. Mitotic figures were noted in the alveolar epithelium, and colchicine enhanced the yield. Of 65 mitotic figures examined in detail, 46 were present in the alveolar epithelium. Epithelial mitoses were confined to type II cells, many of which contained lamellar inclusions, abundant rough endoplasmic reticulum, and luminal microvilli. Mitoses were not seen in type I cells or in less well differentiated epithelial cells, but they were noted in occasional endothelial and interstitial cells. Colchicine-arrested type II cells were distinguished by radially disposed chromosomes surrounding pairs of centrioles and randomly oriented microtubules. In addition, many of these cells showed a pronounced cortical zone, devoid of microvilli, and others showed cytotoxic degenerative changes. These observations indicate that the alveolar epithelium is renewed exclusively by division of differentiated type II cells.
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  • 49
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Two-day-old female rats were injected with 5 nmole/kg of 6,7-3H-11β-methoxy-17-ethylestradiol (R 2858 = moxestrol) and killed one hour later. The animals were decapitated and, the pituitary glands were removed, mounted on tissue holders and frozen in liquified propane. The tissue was then processed for autoradiography according to the thaw mount technique. At the end of the exposure time, prior to photographic development, some of the tissue was fixed in 10% formalin and then photographically developed for autoradiography. The fixed tissue was subsequently stained immunocytochemically using antibodies to luteinizing hormone or prolactin. Between 10 and 15% of the cells of the pars distalis concentrated the synthetic estrogen or its metabolite. The immunocytochemical procedure revealed that both LH-gonadotrophs and lactotrophs concentrated the steroid. These studies along with earlier studies suggest that the neonatal rat pituitary contains only a small portion of the adult complement of estrogen receptors and that these receptors are dispersed across a number of cell types.
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  • 50
    Electronic Resource
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 194 (1979), S. 563-569 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Human third molars were partially demineralized in an acid-alcohol solution and embedded in Epon 812. Six-micron sections were cut from regions of the cervical enamel exhibiting prominent Retzius lines. The plastic was removed from the specimens by microincineration and were examined with the scanning electron microscope. The most prominent structural feature seen along the Retzius lines was the cervical translocation of some of the prisms. The scanning electron microscopic images also suggested that prisms were translocating in the transverse plane of the tooth. A series of pores, which appeared to be empty, were observed in association with the translocations occurring along the Retzius lines.
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  • 51
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The specific granules found in the atrial cardiac muscle cells of the normal rat were studied. The ultrastructural appearance of these granules demonstrates a fixative-dependent lability. Fixation with cacodylate buffered aldehydes yields three types of granules. However, fixation with phosphate buffered aldehvdes or primary fixation with OsO4 yields granules of uniform appearance. The granules are found predominantly in the perinuclear zone; 78% of the granules are within ten linear micrometers of the center of the nucleus. Two independent methods of measurement demonstrate spherical diameters of these granules of 0.30 μm and 0.37 μ respectively. The granules are found in greater concentration at one pole of the nucleus than at the other. On the high density side there are 4.07 granules/μm3 which occupy 5.8% of the cytoplasmic volume. On the low density side there are 2.15 granules/μm3 which occupy 3.0% of the cytoplasmic volume. The granules at both poles are the same size. Atrial walls were incubated in a modified Tyrode's solution. One hour of incubation caused no change in the atrial granules. Addition of norepinephrine or L-Dopa resulted in the appearance of more granules but the size of the granules remained the same. Incubation with reserpine had no effect upon the atrial granules. Apparently the atrial myocardial cell is stimulated by exogenous catechol-amine to synthesize more atrial granules which themselves do not appear to contain catecholamines.
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  • 52
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 195 (1979), S. 1-5 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Four rhesus monkey pituitary glands were examined by transmission electron microscopy. Three types of intercellular junctions, desmosomes, hemidesmosomes and zonula adherens-type junctions, were observed between adjacent granular cells, folliculo-stellate cells, and joining a folliculostellate cell with a granular cell. Desmosomes were most commonly observed between granular cells while the zonula adherens-type junctions were generally found between the folliculo-stellate cells.
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  • 53
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 195 (1979), S. 387-395 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Carotid bodies from adult rats were electron microscopically studied after incubation in glucose-containing salt solutions containing calcium and/or ionophore A23187 or neither. In the absence of the ionophore, adding or omitting calcium had no effect on the fine structure of theglomus cells. Incubation in the medium containing both 1 mM calcium and the ionophore caused the appearance of exocytotic membrane profiles in several glomus cells. Exocytosis was not seen when only A23187 and endogenous calcium was present. For exocytosis to occur, calcium appeared to be essential and the event seemed to be due to a rise in the intracellular calcium concentration caused by the ionophore.
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  • 54
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 195 (1979), S. 415-428 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Hyperglycemia (experimental diabetes) was induced in adult male rats by destruction of the pancreatic beta cells with a single intravenous injection of streptozotocin (STZ). Testes from diabetic, from insulin-treated diabetic, and from sham-injected normal rats were fixed by vascular perfusion. The fine structure of Leydig cells was examined at two, three, and four weeks after the STZ injection in the untreated diabetic animals, and at four weeks in the controls and insulin-treated diabetic rats. A number of morphological changes was observed in Leydig cells of untreated diabetic animals. Most obvious of these was an accumulation of lipid droplets, not normally present in Leydig cells in adults of this species. Smooth endoplasmic reticulum (SER) was markedly reduced in Leydig cells of the hyperglycemic rats. Several types of intracellular bodies were seen exclusively in Leydig cells of the untreated diabetic animals. Many resembled secondary lysosomes or dense bodies, while others appeared to be autophagic vacuoles. In addition, a small, granule-containing lamellar structure was seen either within a typical dense body or free in the cytoplasm. Myelin-like structures were commonly observed within the cytoplasm of the Leydig cell or within mitochondria. The appearance of the mitochondria in diabetic rats was otherwise normal. The extracellular spaces surrounding Leydig cells from untreated hyperglycemic rats also contained large accumulations of myelin-like material. These structural changes appear to be direct consequences of the diabetic state of the animals, since the ultrastructure of insulin-treated diabetic rats did not differ from that of the controls. These findings may reflect an alteration or breakdown of Leydig cell components normally involved in the synthesis of androgen, and correlate with previous reports of lowered circulating levels of testosterone in diabetic rats.
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  • 55
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The morphologic response of periodontal ligament (PDL) cells in an area of tension created by orthodontic force has been assessed by transmission electron microscopy. Young adult male rats were sacrificed at 24, 48, 72, 96 and 120 hours following orthodontic stimulation. The earliest detectable response was the appearance of increased numbers of mitotic cells in the PDL at 24 hours post-stimulation. The most significant ultrastructural feature of these cells was the presence of intracellular vesicles containing collagen microfibrils. These vesicles were identical to profiles present in interphase PDL fibroblasts involved in collagen phagocytosis associated with turnover of the ligament. Between 48 and 120 hours the alveolar bone surface in the region examined was characterized by the presence of newly generated osteoblasts and active bone formation. Intracellular collagen was never observed in osteoblasts. These observations suggest that at least a portion of the population of PDL cells which proliferate in response to orthodontic force represent functional ligament fibroblasts.
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  • 56
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 195 (1979), S. 447-453 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The pennate flexor carpi radialis muscle of the cat has been shown to have a compartmentalized distribution of muscle fiber types. The possibility exists that the oxidative regions of the FCR are primarily concerned with fine movements including postural adjustments, while fast-twitch glycolytic region is used more for phasic movements. Muscle fiber diameters were measured for all three fiber types to determine if there was a compartmentalization of fiber size that might reflect differences in motor performance between the different regions of the same muscle. This study has demonstrated that the oxidative fiber types are significantly larger in the oxidative compartment when compared with the same fiber types in the glycolytic compartment and that the cross-sectional area of the oxidative region is dominated by oxidative fibers. The glycolytic fibers are significantly larger in the glycolytic compartment when compared to those in the oxidative region of the muscle and they constitute the major fiber type in this region.
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  • 57
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Samples of the rectus abdominis muscle were taken from Sprague-Dawley rats at 0, 3, 6, 9, 12, 15, 18, and 21 days of pregnancy, and at 1, 3, 6, 9, 12, and 15 days of postpartum. Sections were incubated for actomyosin adenosine triphosphatase activity following preincubation at a basic pH. Muscle fibers within a unit area of each sample were identified as to fiber type according to their enzyme activity, and the population of each type counted. The proportion of each fiber type was calculated and the diameter of 24 fibers of each type measured. No changes were noted in the muscle fiber proportions through the course of the experiment. Differential changes in muscle fiber diameters were noted in each of the three muscle fiber types. Slow oxidative fibers underwent an increase in diameter through the last half of pregnancy. The diameter was further increased as stretch of the muscle was released after birth, and did not decrease in the postpartum period. Fast glycolytic fibers decreased in diameter during the last half of pregnancy, but returned to the prepregnancy diameter in the first postpartum day. The diameter of the fast oxidative glycolytic fibers remained unchanged through the course of pregnancy and in the postpartum period.
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  • 58
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Models of the lung airways of a rat were developed from complete measurements of the tracheobronchial airways. A silicone rubber cast of the tracheobronchial airways of a rat lung was prepared and all individual airway segments down to and including the terminal bronchioles were measured to obtain the segment diameters, lengths, branching angles and angles of inclination to gravity. Models of the rat tracheobronchial airways were constructed based on the original measurements and the subsequent analysis. Some mathematical assumptions about acinar anatomy distal to terminal bronchioles were made to extend the models to include pulmonary regions. Emphasis was placed on the “Typical Path Lung Model” which used one typical pathway to represent either a whole lung or a lobe of the lung. The models are simple and can be applied in calculation of physiologic variables or particle deposition during inhalation in various lobes of the lung.
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  • 59
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: We describe the sequential ultrastructural changes in villus absorptive cells of human fetal small intestine between 9 and 22 weeks of gestation. In concert with villus formation at 9 to 10 weeks, a complex membranous system designated the apical tubular system appeared in the apical cytoplasm of absorptive cells. The apical tubular system consisted of deep invaginations of plasma membrane and membrane-bounded vesicles and tubules. Some elements of this system were characterized by linear arrays of particles on the inner (luminal) membrane leaflet. After villus formation, many lysosomal elements designated “meconium corpuscles” also appeared in the apical cytoplasm. Modified morphometric studies suggested that both the apical tubular system and the lysosomal elements were more extensively developed in the distal than in the proximal intestine, were most abundant at 15 to 17 weeks, and decreased by 18 to 22 weeks. Morphometry also showed an inverse relationship between the relative surface density of the apical tubular system and microvillus membrane, suggesting the possible derivation of elements of the former from the apical plasma membrane. Exposure of intestine to ferritin for 8 to 40 minutes in vitro revealed ferritin in elements of the apical tubular system of 12- to 20-week fetuses. There was no evidence of transport of ferritin across absorptive cells. Distinctive membranous bodies composed of convoluted membrane-bound cisternae separated by narrow channels of cytoplasmic matrix were seen in the Golgi region and apical cytoplasm of fetal absorptive cells between 14 and 22 weeks. In a single 22-week fetus, there was marked proliferation of smooth endoplasmic reticulum, a decrease in cytoplasmic glycogen and loss of most lysosomal and apical tubular elements in the proximal but not the distal intestine. Thus, by the end of the second trimester, the structure of absorptive cells in proximal intestine was remarkably similar to absorptive cells in adult intestine.
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  • 60
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    The @Anatomical Record 195 (1979), S. 493-509 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The yolk sac of the Indian fruit bat Rousettus leschenaulti is unique since during the course of development it become converted into a solid, richly vascular endocrine gland-like structure with both the endodermal and mesothelial cells undergoing substantial hypertrophy. The yolk sac is progressively drawn from the abembryonic (antimesometrial side) to the embryonic pole (mesometrial side) of the chorionic sac where in late stages it comes to rest against the placental disc. The endodermal cells become grouped into clusters of acinus-like structures surrounded by the columnar mesothelial cells; the yolk-sac lumen is in most instances obliterated. Individual endodermal cells are large in comparison to mesothelial cells. The endodermal cell population varies between cells with abundant agranular ER and areas devoid of organelles to others with dense cytoplasm containing stacks of granular ER. All endodermal cells have numerous mitochondria and a few lipid droplets.The mesothelial cells are columnar with either dome-shaped, pointed or flattened apices bearing numerous elongate microvilli; within these are parallel-arranged microfilaments. While the apical cytoplasm shows the presence of absorptive tubules. coated vesicles and caveolae, the basal cytoplasm contains a few small mitochondria. Some mesothelial cells contain lipid droplets in their basal cytoplasm. On structural bases it is postulated that the mesothelial cells are absorptive in function while the endodermal cells are synthetic and secretory.
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  • 61
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Gastric mucosa of an elasmobranch species was examined by electron microscope. The gastric glands contain one form of cell whose fine structure is similar to the cell that secretes both hydrochloric acid and pepsinogen of the amphibian gastric glands proper. These oxynticopeptic cells are characterized by: (a) a luminal surface with long projections of cytoplasm having dilatations in their thickness; (b) a tubulo-vesicular system in the apical cytoplasm; (c) a great number of mitochondria, some of which are of great length; (d) a well developed granular endoplasmic reticulum and a conspicuous Golgi apparatus; and (e) a large nucleus with a conspicuous nucleolus. A fourth part of the cells are binucleated. Physiological implications of some of these ultrastructural features are discussed.
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  • 62
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The distribution and cytological characters of physiological cell death associated with formation of the lens vesicle in the chick embryo was studied by means of vital staining, light and electron microscopy.We have established a constant pattern of cell death which differs in some aspects from that reported for mammals and amphibians. The necrotic process is observed initially in the dorsal part of the lens cup (stage 15). The necrotic area progressively surrounds the lens pore as invagination proceeds (stage 16) and at stage 17 is located in the zone of fusion of the invaginated lens. After detachment of the lens (stages 18, 19 and 20) dead cells appear in the ectoderm, in the superficial epithelium of the lens vesicle and in the space between both structures.Ultrastructurally we observe isolated dead cells in different stages of degeneration and in phagocytosed cells. Phagocytosis is carried out by the neighboring healthy epithelial cells. Phagocytic activity was detected concomitant with the beginning of the necrotic process. Cell fragments were occasionally detected within the lens cavity.
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  • 63
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A morphologic investigation of ependyma over gray matter (caudate nucleus) and over periventricular white matter (tapetum) of the rabbit lateral ventricle was undertaken prior to evaluation of morphological changes which occur with experimental hydrocephalus. Ependymal cells over the caudate nucleus are cuboidal and heavily ciliated. Numerous microvilli cover the cell surface. The lateral margins are straight and interdigitations between adjacent ependymal cells are absent. Ependymal cells over white matter are squamous. Nonciliated as well as ciliated cells contribute to the epithelial lining. Microvilli are present at the cell surface but tend to aggregate near the cellular borders. The lateral margins are convoluted and complex interdigitations are present between adjacent cells. Morphologic differences between ependymal cells over the caudate nucleus and those over periventricular white matter may help to explain the differential response to hydrocephalus observed in these two regions of the lateral ventricle.
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  • 64
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: It has been proposed that thyroid hormones may have a role in the regulation of lung development and the maturation of the surfactant system. The purpose of this study was to examine the effects of exogenous thyroxine (T4) on rat lung development and to investigate possible interactions of this hormone with the glucocorticoids, other hormones implicated in the regulation of lung development.A number of different experimental protocols were utilized: T4 was administered to day 17 and 18 rat fetuses from untreated animals as well as from animals which had been adrenalectomized or treated with the 11-β-hydroxylase inhibitor, Metopirone; replacement hydrocortisone was administered to some groups. Sham-operated and untreated animals were included as controls. Animals were sacrificed from days 19-22 (term, day 22-23) of gestation and the fetal lungs were examined. Accelerated lung development was observed in all experimental groups receiving T4. Alveolar epithelial cells were more differentiated in comparison to controls. Glycogen deposits were diminished, cell flattening was more advanced, mitochondria, Golgi complexes and rough endoplasmic reticulum were more prominent, and lamellar bodies, storage sites for pulmonary surfactant, were greatly increased in number. Secretion of lamellar bodies into the alveolar space was also stimulated. The results also indicated that T4 and glucocorticoids act together in the acceleration of lung development. Under conditions of decreased glucocorticoids (Metopirone treatment and adrenalectomy), stimulatory effects of T4 were still evident but less pronounced; hydrocortisone replacement increased the observed stimulation. Maximal acceleration of lung development was observed subsequent to T4 and uncontrolled surgical stress. These results demonstrate that T4 can accelerate rat lung development and that this acceleration is maximal in the presence of glucocorticoids.
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  • 65
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    The @Anatomical Record 194 (1979), S. 83-103 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A morphologic investigation of ependyma over gray matter (caudate nucleus) and over periventricular white matter (tapetum) of the rabbit lateral ventricle was performed four months after the induction of experimental hydrocephalus. Ependymal cells over the caudate nucleus are not modified by hydrocephalus. They remain cuboidal and heavily ciliated. Numerous microvilli cover the cell surface. The extracellular space of the neuropil is not expanded. Ependymal cells over the periventricular white matter are markedly modified. The characteristic response of these ependymal cells is to enlarge and to form lacunae in their apical cytoplasm. Their apical, horizontal cytoplasmic processes elongate as adjacent ependymal cells separate. The ex-tracellular space of the neuropil is expanded.It is proposed that the changes seen in ependymal cells over periventricular white matter are a response to enlargement of the ventricular surface permitted by the orientation of neuronal and glial fibers parallel to the ventricular surface. With expansion of the ventricular surface, overlapping apical processes become elongated and modified, containing a terminal web. With further enlargement, sliding of an overlapping apical process of one cell uncovers the apical process of its neighboring cell. By this mechanism, the ventricular surface area of any ependymal cell whose surface has been partially covered by its neighbor is increased. With further progression, this compensation fails and the neuropil is exposed to the ventricular cavity.Over caudate nucleus, expansion of ventricular surface is hindered by the disposition of fascie adherentes along intercellular clefts oriented perpendicular to the ventricular surface. Lateral sliding of horizontal apical processes does not occur as such processes are not found in ependyma over the caudate nucleus.The differential response of the ventricular surface in these two areas characteristically seen in hydrocephalus is; determined by regional differences in the morphology of their ependymal cells and underlying neuropil.
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  • 66
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 194 (1979), S. 105-111 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The fine structure of the mouse adrenal cortex was examined with the electron microscope for the presence of neural elements. Several axon terminals containing mostly clear vesicles (60 nm) were noted in the vicinity (250 nm) of the capsular fibroblasts. In the subcapsular region, myelinated as well as unmyelinated fibers were commonly found. Preterminal and terminal axons were also found in close relationship to the parenchymal cells in the zona glomerulosa. Nerve bundles were the most common neural elements in the zona fasciculata. In the zona reticularis axon terminals containing both clear (60 nm) and dense core (120 nm) vesicles were seen in close proximity (30 nm) to parenchymal cells. Although this study did not delineate the type of fibers involved, the axon terminals resemble those of autonomic nerves.This study demonstrates innervation of the mouse adrenal cortex, thus corroborating similar reports by others in different species.
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  • 67
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    The @Anatomical Record 194 (1979), S. 113-123 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Mice fed a high cholesterol-cholic acid (lithogenic) diet for one year develop fatty livers in addition to gallstones. Light and electron micrographs demonstrate large amounts of lipids in liver parenchymal cells, often to the exclusion of most other cytoplasmic organelles. In addition, some hepatocytes exhibit nuclear lipid pseudo- and true inclusions. Other prominent features of hepatocytes after lithogenic diet include segregation of nucleolar granular and fibrillar material. Accumulation of considerable collagen in extracellular spaces is also noted. Observations suggest changes induced by the cholesterol diet are comparable to cytologic alterations seen in spontaneous and drug induced hepatic tumors, as well as to more general “fatty metamorphosis” of the liver.
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  • 68
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The type II pulmonary epithelial cell is the recognized site of surfactant synthesis and storage. Results of recent studies indicate that the thyroid hormones, triiodothyronine (T3) and thyroxine (T4), may be important regulators of surfactant production and/or release. Direct and indirect immunofluorescence techniques were used in an attempt to demonstrate binding of T3 and T4 in monolayer cultures of isolated type II cells. These cultured epithelial cells are clonally-derived from adult rat lung, retain a diploid karyotype through 35 population doublings in vitro, contain granular inclusions (lamellar bodies) in the perinuclear cytoplasm, and synthesize phosphatidylcholine via the CDP-choline pathway.In isolated type II cells, either of two fluorescent patterns was observed: (a) nuclear fluorescence accompanied by a reticular perinuclear network; or (b) diffuse cytoplasmic accumulations with concentrations around perinuclear cytoplasmic inclusions. Ultrastructurally these inclusions had the typical appearance of lamellar bodies. Histochemical studies demonstratedthat these inclusions contained surfactant-associated nonspecific esterases and stained with Nile blue hydrochloride. The positive reactions with these two recognized markers for pulmonary surfactant indicate that these inclusions are indeed lamellar bodies, the putative sites of surfactant synthesis and/or storage. These findings suggest that the type II pulmonary epithelial cell contains specific binding sites for thyroid hormones, and support the hypothesis that thyroid hormones are regulators of surfactant metabolism.
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  • 69
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    The @Anatomical Record 194 (1979), S. 181-185 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Transventricular filaments were observed with scanning electron microscopy on the dorsolateral wall of the infundibular recess of the third ventricle of the armadillo brain. Two to seven transventricular filaments per animal were present in 6 of 18 animals. There were two types of transventricular filaments, ciliated and bare. Using transmission electron microscopy, we determined that these filaments consisted of a single, central capillary surrounded by ciliated ependymal cells and a small accumulation of axons in five animals. In one animal, a bare filament had a central capillary surrounded by a large accumulation of axons with no surrounding ependyma. The consistent location and structure of these filaments indicate a possible function for a small vascular network, as well as a possible commissural network connecting right and left hypothalami in the region of infundibular nuclei.
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  • 70
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    The @Anatomical Record 193 (1979), S. 233-241 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The ultrathin sections of the developing otolith of mouse fetuses 15.5 days to 20 days after birth were observed with the aid of the electron microscope.The first step of otolith formation is an aggregation of organic clusters observed in the sacculus of the 15.5-day fetus. These organic structures are modified and assume a hexagonal shape in the 17.5-day fetus. The unmineralized stages of the otolith referred to as the preotolith, serve as the template for future development.One day after birth, at either end of the preotolith, minute tube-like structures develop in which needle-shaped crystallites are initiated. Crystallites continue to develop throughout the hexagonal template which give rise to a structure containing many regularly arranged needle-shaped crystallites. Based on the present observations, the mouse otolith is considered a multi-iso-oriented crystal.
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  • 71
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The ultrastructure of the adrenocortical homologue (AH) of the north American eel (Anguilla rostrata) was studied from freshwater and long-term (1.5 years) seawater (SW) adpated animals. The AH tissue situated in the wall of cardinal veins is surrounded by a thin layer of collagenous capsule; in the region away from the vein wall, parenchymal cells are separated by interstitial lacunae containing collagen bundles, capillaries, chromaffin cells and nerve fibers often applied closely to the surface of AH cells. The free surface of the cell near the vein wall, capillaries or interstitial space extends numerous slender microplicae. The cytoplasm is characterized by the presence of mitochondria with tubular cristae, a network of smooth endoplasmic reticulum, a few cisternae of rough surfaced endoplasmic reticulum, well developed Golgi apparatus, coated vesicles, centrioles, cilium, filaments, microtubules, dense bodies of variable nature and a scarcity of liposomes. The cell nuclei possess invaginated cytoplasmic pseudo-inclusions. Electron histochemical reaction for free cholesterol revealed the occurrence of needle-shaped crystals mainly associated with surface microplicae and smooth endoplasmic reticulum, which seems to be the major organelle for storage or synthesis of this steroid precursor. SW animals indicated ultrastructural signs of stimulated steroid synthesis and secretion, i.e., high degree of pseudo-follicle formation, increased electron density of mitochondria, greater abundance of lysosomal dense bodies, hyperactivity of Golgi apparatus and dilation of smooth endoplasmic reticulum tubules. Some SW fishes showed extensive deposition of osmiophilic inclusions in the mitochondria and stacks of elongated cup-shaped mitochondria. Chronic seawater acclimation enhances AH activity as judged by ultrastructural criteria with ultimate mitochondrial degeneration resulting possibly from prolonged cortisol hypersecretion; the latter may be linked with physiologic re-adjustment of ionic transfer mechanism in hyperosmotic medium.
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  • 72
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    The @Anatomical Record 193 (1979), S. 243-255 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The appearance of the spermatid Golgi apparatus was studied, both in thin sections of rat testes fixed in glutaraldehyde and treated with either tannic acid or ferrocyanide-reduced osmium, and in relatively thick sections (0.25-0.5 μm) of glutaraldehyde fixed tissue impregnated with uranyl acetate followed by lead and copper citrate. With any one of these three procedures, the Golgi apparatus of young spermatids examined at the Golgi and cap phases appeared as a compact hemispherical mass whose base was located next to the developing acrosomic system. The cortical region of the hemisphere was composed mainly of several stacks of saccules. The central core or medullary region contained numerous vesicular and tubular membranous profiles. Numerous cisternae of the endoplasmic reticulum (ER) were closely applied to the surface of the Golgi apparatus. In thin sections, the ER cisternae were separated from the stacks of saccules by small spherical or elongated membranous profiles. In thick sections, most of these elements formed a network of tubules, some of which being continuous with ER cisternae. Cisternae of the endoplasmic reticulum near the cis-face of the Golgi stacks also branched and traversed the cortical region of the Golgi apparatus through gaps seen between the stacks of saccules to reach the central core region. Some of these were closely applied to the trans elements of Golgi stacks although never in continuity with them. Finally, ER cisternae were found located within the stacks themselves between Golgi saccules; here the membranes of the closely apposed cisternae of the endoplasmic reticulum and Golgi saccules remained separated by a space of about 12 nm. Thus, in the spermatid, the endoplasmic reticulum was closely related with all components of the Golgi apparatus.
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  • 73
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    The @Anatomical Record 194 (1979), S. 429-443 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The ultrastructure of the urethral epithelium and mesenchyme of the 6- to 9-week-old human embryos was studied in order to reveal early morphological signs of prostatic development. The morphological changes of the urethral wall were correlated with the cytodifferentiation of the Leydig cells of the same embryos. Throughout the study the urethral epithelium had two or more layers of cuboidal cells. The ultrastructure of the cells was primitive and they did not achieve characteristics of the secretory prostatic cell. The surface cells had well developed apical junctions and slender cytoplasmic processes projecting into widened intercellular spaces appeared during the developmental period. The urethral mesenchyme showed the most salient changes. The mesenchymal cells adjacent to the urethral epithelium differentiated in the ninth week into fibroblast-like cells with an elongated shape and cytoplasmic processes. Granular endoplasmic reticulum appeared in the cytoplasm and collagen fibers were seen in the intercellular space. Mesenchymal cell processes contacting the continuous basal lamina under the epithelium were present. No direct epithelio-mesenchymal cellular contacts could be seen. The differentiation of the mesenchyme before the epithelial outgrowths suggests that the mesenchyme has an essential role in the glandular development.Electron microscopic study of the Leydig cells showed that the amount of agranular endoplasmic reticulum increased considerably in the ninth week. This agrees with earlier biochemical findings on the capability of Leydig cells to produce androgens by this time. The temporal relationship between the cytodifferentiation of Leydig cells and the urethral wall is consistent with the idea that in the human, fetal androgens induce prostatic development.
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  • 74
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    The @Anatomical Record 194 (1979), S. 445-459 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The parenchymal components of rat submandibular gland were examined by scanning electron microscopy after removal of the stromal connective tissue by acid hydrolysis and/or enzymatic digestion. Secretory acini have polymorphous topographies but usually consist of three to five truncated lobes emanating from a common hilus. They have a mean volume of about 33,000 μm3. Myoepithelial cells are associated with the deeper acini of the gland where they cover ⋍ 54% of the surface area of their allied acini. Each flattened myoepithelial cell has a central perikaryon that gives rise to four or five broad primary processes that bifurcate two or three times to produce a total complement of 20 to 40 terminal processes per cell, each 0.5 μm to 1.7 μm wide. The terminal processes of adjacent myoepithelial cells tend to slightly overlap and to attach to each other by desmosomes forming a network over adjacent acini. The components of the duct system are examined and each characterized by salient features as observed with the SEM.
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  • 75
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    The @Anatomical Record 194 (1979) 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 76
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    The @Anatomical Record 193 (1979), S. 293-311 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Rat spermatozoa are highly dependent on the milieu of the normal epididymis for their maturation and survival, and die within a few days after androgenic support of the epididymal epithelium is withdrawn. The immediate changes in the ultrastructural organization of the epithelial cells of the rat epididymis, 2, 4, 6 and 14 days following castration have been monitored by morphometric analysis of localized regions of the caput and cauda epididymidis. While castration results in greater endocytosis by principal cells (Moore and Bedford, '79), many of their early structural changes following androgen withdrawal (disappearance of vesicles from the cell apex, reduction in rough endoplasmic reticulum, a drop in the volume of the Golgi cisternae and increase in lysosome content) seem indicative of inhibition of a secretory function. By contrast with the regressive response of the principal cell, the ultrastructure of clear cells in the cauda and of apical cells in the caput region appeared unchanged up to 14 days after castration. The implications of this evidence for specialized functions, and the suggestion of a differential androgen dependence among major cell types of the epididymal epithelium, are discussed briefly.
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  • 77
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    The @Anatomical Record 194 (1979), S. 355-367 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Juvenile mice were treated for up to eight weeks with weekly doses of a synthetic analogue of cortisol:triamcinolone hexacetonide. The mandibular condylar cartilage was studied histologically and histochemically at regular intervals. Morphometric measurements were performed along the mandibular posterior vertical dimension (condylar process and ramus). By the second injection significant morphological changes were noted in the condylar cartilage, followed by retardation of bone growth. The most distinctive feature in the cartilage of triamcinolone-treated mice was a marked increase in the dimension of its mineralized zone concomitant with a significant increase in the number of hypertrophic chondrocytes. The role of condylar cartilage in mandibular growth is discussed.
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  • 78
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    The @Anatomical Record 194 (1979), S. 369-387 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The accumulation of non-vascular, non-neuronal cells (designated herein as reactive cells) in association with perikarya of axotomized motor neurons has been described by many investigators. Recently Gilmore ('75) found that sciatic axotomy in immature rats resulted in the occurrence of reactive cells not only in the spinal ventral gray matter but also in the dorsal gray matter. To determine if the presence of these cells in the dorsal gray matter, a finding not reported by others, was related to the immaturity of the animal, sciatic axotomy was performed in rats ranging in age from 17 days to 16 months in the present study. Light microscopic evaluation of the spinal cords three or seven days post-operatively showed that the reactive cells occurred consistently in both dorsal and ventral gray matter irrespective of age. Transection of tibial nerve or the nerve to the medial head of the gastrocnemius muscle elicited a cellular response in both dorsal and ventral gray matter, although transection of the latter nerve resulted in a much less obvious response. Crushing of the sciatic nerve was followed by a response of reactive cells not qualitatively different from that noted following transection. Transection of the sural nerve, primarily a sensory nerve, resulted in the presence of reactive cells in dorsal gray matter but not in the environs of motor neurons in the ventral gray matter. These findings suggest that the reactive cells in the dorsal gray matter of the spinal cord are associated with altered central processes of dorsal root ganglion cells.
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  • 79
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Atrophy of zona reticularis cells was observed two weeks after surgical thyroparathyroidectomy (TPX). Quantitative morphological techniques for electron microscopy showed significant decreases in the volume of cytoplasm, nucleus, mitochondria, smooth endoplasmic reticulum and lipid droplets in the zona reticularis of TPX rats. In addition, many mitochondria contained lipid droplets, some of which occupied virtually the entire matrix of mitochondria. The volume per cell of mitochondria with these inclusions increased significantly after TPX. The lipid droplets may well arise from cytoplasmic droplets by increased transport or reduced metabolism of cholesterol, or by direct incorporation of droplets into the mitochondrial matrix. The serum corticosterone level of TPX rats sacrificed under quiescent conditions did not differ significantly from that of controls. Hypothyroidism induced a significant increase in the volume of peroxisomes per cell in TPX animals which may be related to changes in lipid metabolism or transport.
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  • 80
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Serial sections of normal human embryos were studied and three-dimensional images reconstructed to determine the early development of the interventricular septum. The position of the interventricular septum is determined in stage 9 of normal development by the formation of the left interventricular sulcus. As a result of unknown properties of the cells of the myocardial layer, the left interventricular sulcus persists while the right disappears, producing the initial lateral asymmetry of the primary heart tube. By stage 14, the left interventricular sulcus forms a spiral which is continuous with the developing interventricular septum. The dorsal limb of the spiral passes to the right between the atrioventricular canal and the origin of the outflow tract, and is lost in the wall of the trabeculated right ventricle. It appears that this dorsal limb of the spiral is the precursor of part of the cirsta supraventricularis. The midportion of the sulcus, the bulboventricular groove, becomes the socalled fibrous continuity between the aortic and mitral valves. The ventral limb of the spiral passes caudally in the anterior interventricular groove and then dorsally and cranially toward the dorsal cushion of the atrioventricular canal. The ventral limb of the spiral is continuous with the crest of the muscular interventricular septum, which develops by apposition of tissue from the expanding right and left ventricles. From stage 14 to stage 19, the muscular interventricular septum, the atrioventricular endocardial cushions, and the ventricular end of the spiral ridges of the outflow tract appose and fuse. Subsequent formation of the membranous interventricular septum completes the physical separation of the right and left ventricles.
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  • 81
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    The @Anatomical Record 194 (1979), S. 461-468 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The renal morphology of three species of desert dwelling Perognathus rodents were compared to Dipodomys and two species of sympatric cricetid rodents. Perognathus has a highly adapted unipolar kidney capable of urine concentration up to 7,500 mOsm/KgH2O. Two major modifications were observed in these kidneys. (1) There is elongation of both the inner and outer medulla. When the thickness of the regions in P. penicillatus are factored by kidney weight it is found that the outer medulla is 3.8 and the inner medulla is 2.2 times greater in length than the extensively studied Dipodomys merriami. (2) There is great variance in glomerular size with approximately 20% of the glomeruli being very large and located in the juxta medullary region. These glomeruli are 1.5-1.6 times greater in diameter than the more numerous superficial glomeruli. These structural modifications are quantitated and the functional implications are discussed particularly in relation to urine concentrating ability in these desert inhabitants.
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  • 82
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    The @Anatomical Record 194 (1979), S. 469-475 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Whether neural crest cells from the avian embryo are determined for chondrogenesis before they begin their migration away from the neural tube (i.e., before H. H. stages 8.5-9) was investigated by establishing neural folds from embryos of H. H. stages 5-11 either in organ culture, or as grafts to the chorioallantoic membranes of host embryos. Cartilage differentiated from neural folds taken from embryos of H. H. stages 5-7 but not from those taken from older embryos. This stage specific pattern was reversed when the tissue adjacent to the neural tube was grafted to the chorioallantoic membrane. Cartilage only formed from tissues isolated later than H. H. stage 8; i.e., when these adjacent tissues contain neural crest cells. We concluded that neural crest cells are determined for chondrogenesis while still in the neural tube and before their migration to the face and head. This is in contrast to the situation in the only other group which has been examined, the urodele amphibians.
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  • 83
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    The @Anatomical Record 194 (1979), S. 491-505 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The jejunal mucosa of neonatal rats contains lipid particles of the same size, electron density and intracellular and extracellular distribution as particles identified by others in adult jejunum as lipoprotein particles. As in fetal jejunum obtained during the last three days of gestation, the jejunal mucosa of unsuckled newborn rats contains exclusively lipoprotein particles the size of very low density lipoproteins (VLDL). Within one day after initiation of suckling, there is in the mucosa a spectrum of lipoprotein particles ranging widely in size from those of VLDL particles to those of chylomicrons. These particles are seen in the endoplasmic reticulum and Golgi material of absorptive cells and within interepithelial cell spaces, the extracellular spaces of the lamina propria and lymphatic lacteals. VLDL-sized and chylomicron-sized particles are also seen, although in decreasing number, in the jejunal mucosa of 18-day-old suckling rats. However, in rats of comparable age, fasted for 48 or 72 hours, only VLDL-sized particles are seen in the jejunal mucosa. Ligation and transection of bile duct followed by fasting in rats of this age results in a marked decrease in the number of lipoprotein particles in absorptive cells. The results indicate that endogenous lipid contributes to the formation of VLDL particles whereas dietary triglycerides are needed for formation of chylomicrons.
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  • 84
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    The @Anatomical Record 194 (1979), S. 511-522 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The study (i) describes a method for estimating relative changes in membrane surface areas as they occur in stereological “average cells,” and (ii) considers the effect of the controls on these estimates. The results indicate that changes in five membrane compartments of pancreatic exocrine cells-produced by a secretagogue (carbomylcholine chloride)-were detected similarly when related to either an average cell surface (surface area ratio method) or to an average cell volume (method of Loud, '68). Changes, however, detected with surface densities, which relate these membrane compartments to 1 cm3 of exocrine cell cytoplasm or pancreas, were notably different from the first two estimates. This inconsistency could be explained by the fact that the surface densities were influenced not only by membrane changes within the exocrine cells, but also by changes in the number of these cells filling the cm3 of reference volume. Relating the data to an average cell reference-instead of 1 cm3-improved the accuracy of the estimates for changes in membrane surface areas by as much as several fold; the choice of controls had a similar several-fold effect on the results.
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  • 85
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    The @Anatomical Record 195 (1979), S. 573-573 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
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  • 86
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    The @Anatomical Record 193 (1979), S. 357-365 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The extracellular space of mouse ovarian follicles and stroma contained horseradish peroxidase (HRP) reaction product one minute after intravenous injection of the tracer. In addition to pinocytotic uptake of the tracer, non-vesicular staining with HRP reaction product, heretofore unrecognized, was noted in a variety of ovarian cell-types. This diffuse staining was correlated with changes in cellular morphology suggestive of degeneration. These findings are discussed in relation to the composition of cell populations comprising follicles and ovarian stroma and alterations in cell function.
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  • 87
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    The @Anatomical Record 193 (1979), S. 367-381 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Distinctive linear arrays of intramembrane particles were present in microvillar membranes of approximately 5% of surface columnar cells observed in freeze-fracture replicas of monkey colon and human rectum. On these cells, longitudinally-oriented rows of P face particles and corresponding E face grooves appeared on all exposed microvilli. The constituent particles varied from round (8-9 nm in diameter) to rod-shaped (18 nm long). Microvilli of the great majority of columnar cells displayed randomly distributed P face particles similar to those previously observed in small and large intestine of birds and small mammals. The significance of the linear arrays is not known. It is postulated that they may represent protein assemblies which are specific to a functionally-distinct subpopulation of primate intestinal columnar cells.
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  • 88
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The steady decline in plasma progesterone level that occurs during the last week of pregnancy in the normal rat (Wiest, '70) provides good opportunity to study the effect of withdrawal of progesterone on uterine differentiation. Evidence is presented that tissue monocytes, heterophils, and eosinophils are regular components of the normal late gestational uterus and that their number increases as term approaches. Uterine monocytes and heterophils are located in the endometrial and myometrial stroma as well as within the basal intercellular compartment of the luminal epithelium. Stromal monocytes are distributed throughout the attenuated endometrium of late gestation, but are more common immediately beneath the luminal epithelium. In the myometrium, monocytes and heterophils occur, often as perivascular clusters, in the connective tissue septum that separates the two layers of smooth muscle. Eosinophils are present especially in the deep endometrial and myometrial stroma, and increase in number as plasma estrogen rises immediately before parturition. A small population of lymphocytes is regularly present.An important feature of the prepartum uterine stroma is the sparseness of macrophages. Near term, however, the beginnings of monocytic-macrophagic transformation are noticeable as the cell surface becomes more irregular and organelles associated with endocytic activity arise. The prepartum monocytes are positioned in the same histological sites that during the postpartum period of regression will be occupied by macrophages (Padykula and Campbell, '76). Since it is generally accepted that monocytes are precursors of macrophages, this spatial correlation raises the possibility that cellular preparations for regression commence before birth. The possible significance of prepartum monocytic infiltration is discussed in relation to the effect of changing plasma and uterine concentrations of progesterone on uterine collagenase activity. The steady increase in uterine tissue leucocytes which occurs concomitantly with decreasing uterine binding capacity for progesterone supports the hypothesis by Siiteri et al. ('77) that progesterone in high local concentrations has an antiinflammatory effect.
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  • 89
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    The @Anatomical Record 193 (1979), S. 383-387 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Regeneration of the rat kidney was observed for six days after inducing acute tubular necrosis of the proximal pars recta with d-serine (80 mg/100g body weight). Regenerating cells appear by two days post-treatment, and re-epithelialization of the nephron is completed within six days, with the most mature cells approaching normal morphology. Regeneration originates from viable cells adjacent to the necrotic zone which divide and follow a template provided by the intact basement membrane. Transient, cytoplasmic regenerative activity among developing tubular cells is characterized by the presence of large, irregularly shaped nuclei, prominent nucleoli, abundant ribosomes and lysosomes, and abnormal mitochondrial configurations. Microfilaments appear to be involved in the formation of apical microvilli and the basal labyrinth of plasmalemmal convolutions. These data suggest that d-serine. inducedacute tubular necrosis of the proximal pars recta may be followed by rapid, patterned regeneration along an intact basement membrane, and that microfilaments are involved in differentiation of cellular morphology.
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  • 90
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The microscopic anatomy of the atrioventricular node, bundle of His, both bundle branches and surrounding fibrous cardiac skeleton was studied in 40 large breed dogs of various ages. In the AV conduction system of all dogs over five years of age there was an increase of fibrous connective tissue, an infiltration of adipose tissue, loss of conduction fibers and focal fibrosis extending from the central fibrous body.Fibrosis was seen in the summit of the interventricular septum posterior to the AV node in dogs of all ages. Chondroid metaplasia was consistently observed in the central fibrous body and the root of the aorta in large breed dogs, including ten Doberman Pinschers of all ages. This metaplasia varied from a few chondroblasts and chondrocytes to mature chondrocytes with mineralization. Bone formation was seen in eight dogs. These changes appeared in close approximation to the cardiac conduction system above the bundle of His. No degenerative changes were seen in the AV bundle. Approximately one-half of the large breed dogs five years of age and older had thickened medial and intima proliferation in the small coronary arterioles supplying the AV node. The results of this study suggest that the presence of cartilage and bone in the central fibrous body is a normal occurrence in large breed dogs at all ages.
    Additional Material: 1 Ill.
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  • 91
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 193 (1979), S. 913-925 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Scanning electron microscopy of the bronchiolar neuroepithelial bodies (NEB's) in the neonatal mouse lungs was undertaken and correlated with the accompanying transmission electron microscopy. The NEB's appeared as isolated organoids along the entire length of the bronchioles, and often were located at the branching points. The boundary of the NEB's was outlined by the ciliated and Clara cells. Both granulated cells and modified Clara cells participated in the formation of the NEB. The modified Clara cells covered most of the surface of the NEB leaving only small oval areas for the exposed surfaces of the specialized cells which contained numerous cytoplasmic granules. Short and regular microvilli projected from the exposed surfaces of the granulated cells, while only sparse microvilli of irregular length were seen on the surfaces of the modified Clara cells.This scanning electron microscopy of the NEB's further established these organoids as separate morphological entities. In addition, the findings that the NEB's could be easily identified with the scanning electron microscope and subsequently dissected out for further studies would help future investigations of their functions which are not clearly known.
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  • 92
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The proliferative response to testosterone propionate in the accessory sex glands of castrated male Balb/c mice has been studied when the glands were intact, and when the glands were unilaterally ablated. The response was analysed by serial measurements of DNA and weight, and by 3H-thymidine labelling techniques. When stimulation is started at three days after castration, most seminal vesicle cells of intact glands carry out DNA synthesis to restore preoperative cell number, whilst the smaller reduction in coagulating gland DNA prior to stimulation results in only about 30% of cells carrying out DNA synthesis to restore former levels. In the unilaterally ablated glands of the 3-day castrates, the cell kinetics of stimulated DNA synthesis and the net accumulation of DNA were similar to the intact glands. A much larger deficit in DNA was apparent in all glands of unstimulated 14-day castrates, resulting in a much larger net accumulation of DNA following testosterone stimulation. No difference between intact and unilaterally ablated glands was detected, and despite prolonged stimulation DNA levels did not exceed preoperative values. Unlike gland DNA levels, gland weights exceeded those of non-castrated mice following prolonged stimulation. However, unilateral ablation did not result in further weight increases in the remaining contralateral glands. It is concluded that the absence of the contralateral sex gland is not detected by the remaining partner during the response to the combined stimuli of a reduction in cell number (resulting from androgen deprivation), and testosterone propionate administration.
    Additional Material: 5 Ill.
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  • 93
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 194 (1979) 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 94
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 193 (1979), S. 927-937 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Morphological and functional studies on cell surfaces have been limited largely to cultured cells because of injury wrought to cells of solid tissues by commonly employed mechanical, enzymatic, or chelator dispersal methods. By using the staphylococcal epidermolytic toxin we avoided this problem; the toxin cleaves the intercellular spaces of human and mouse squamous epithelia without ultrastructural evidence of cytotoxicity. We studied the cell surface topography of neonatal mouse epidermis obtained two hours after injection of highly purified epidermolytic toxin. Immediately after sacrifice intraepithelial surfaces were exposed while the animals were immersed in fixative. Specimens were either freeze-fractured or embedded for transmission electron microscopy, or were critical-point-dried prior to platinum/carbon replication for transmission and scanning electron microscopy. Replicas could be prepared for transmission electron microscopy only if they were first stabilized with parloidion and then cleaned with both bleach and 40% chromate. By using these four complementary morphological methods (freeze-fracture, scanning electron microscopy, transmission electron microscopy of surface replicas, and standard thin sections), we could positively identify external membrane structures. The convoluted surface was studded by tenuous microvilli, scattered 15-20 nm particles, and hemispherical desmosomal mounds. Desmosomal plaques displayed randomly arrayed 15-20 nm globular particles comparable in distribution and density to particles observed in freeze-fractured desmosomes, and suggesting that desmosomal integral membrane particles span the external leaflet of the plasma membrane.
    Additional Material: 2 Tab.
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  • 95
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 194 (1979), S. 1-14 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: By using scanning electron microscopy (SEM) we were able to follow the sequence of ultrastructural alterations of the luminal surface which occurred when specimens of canine carotid artery were subjected to controlled transmural pressures. Specimens of carotid artery were removed from dogs following fixation at experimental pressures ranging from 0 mm Hg to 100 mm Hg. The endothelium of specimens fixed at 0 mm Hg has parallel longitudinal ridges formed by the contraction of the underlying internal elastic lamina. With increasing transmural pressure, the luminal surface undergoes a gradual flattening of the endothelial ridges so that at 100 mm Hg, these ridges have completely disappeared. The observed morphologic changes of the arterial endo-thelium indicate that SEM can provide good ultrastructural information on blood vessels subjected to controlled transmural pressure and that the pressure-dependent alterations must be considered in studies on vascular structure and function.
    Additional Material: 6 Ill.
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  • 96
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 194 (1979), S. 41-65 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Dogs are frequent subjects in experimental studies of renal physiology and pathology in spite of the paucity of information on their normal renal morphology. In this study, gross morphology, light microscopy, and scanning and transmission electron microscopy were used to describe dog renal anatomy. The dog has a multilobed kidney with the medulla fused into an elongate crest and a renal pelvis of elaborate shape. The outer zone of the medulla lacks a definitive outer stripe. The proximal tubule consists of four distinct anatomical segments. Dark cells are abundant in the collecting duct of the inner medulla. The majority of the nephron segments demonstrate remarkable similarities to those of the human kidney and less to those of the kidney of the laboratory rat.
    Additional Material: 28 Ill.
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  • 97
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 195 (1979), S. 683-697 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Superior oblique muscle/trochlear nerve pairs from goldfish of various ages (1-5 years) have been examined light and electron microscopically. The muscle grows by enlargement (longitudinally and transversely) of individual fibers, and by addition of new ones at the rate of about 250/year. The nerve grows by enlargement of fibers, but few and perhaps nonew axons are added. The somata enlarge, and the neuromuscular synapses become much more numerous. The ratio of muscle fibers to nerve fibers increases from about 5 in the young to about 16 in the old fish.
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  • 98
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Activated macrophages phagocytize moribund luteal cells and thus play a central role in the postpartum regression of corpora lutea in guinea pigs (Paavola, '79). When viewed by transmission electron microscopy (TEM), these luteal macrophages exhibit many surface protrusions. To characterize more fully the nature and extent of these evaginations, as well as to gain further understanding of phagocytes in their natural surroundings, luteal macrophages were studied in situ by scanning electron microscopy of regressing corpora lutea. Correlated TEM was carried out to confirm the identity of the various cell types. Even in low power scanning electron micrographs, macrophages are conspicuous, and can be readily distinguished from luteal cells by their surface topography. Luteal cell surfaces bear low ridge-like folds and sparse microvilli. In contrast, macrophages characteristically exhibit highly developed surface projections, the most common of which are knob-like or clubbed processes of varying size and shape. Other distinctive surface modifications displayed by luteal macrophages include long, slender filopodia, and well developed pseudopodia. These processes generally have an uneven distribution over the cell; thus, luteal macrophages may appear polarized with regard to surface activity. Both filopodia and pseudopodia occur in close contact with luteal cell surfaces. In addition, occasional luteal macrophages have surfaces that are covered with large, crater-like depressions. The phagocytosis ofcells and cellular debris by macrophages was also observed. In summary, the highly pleomorphic surface activity of luteal macrophages appears to be correlated with their role in the removal of senescent luteal cells.
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  • 99
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 194 (1979), S. 159-179 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A fine structural study of the normal rat vas deferens was undertaken utilizing perfusion fixation. Morphological features not previously appreciated were revealed using this technique of fixation, and included the following.The rat vas deferens exhibited a gross morphological and microscopic differentiation along its length: A proximal segment was characterized by a thin muscular wall, an epithelium of low height (comparable to that of the cauda epididymidis) and a distended lumen typically filled with an accumulation of sperm; a distal segment exhibited a thick muscular wall, a convoluted mucosa, and a pseudostratified columnar epithelium with long stereocilia extending into the lumen. The transition from the morphology typical of the proximal segment to that of the distal segment was gradual and progressive, marked by an increase in the mass of the muscular wall and in the height and ultrastructural complexity of the epithelium. Clear or “foamy” cells, characteristic of the cauda epididymidis, were observed in the initial centimeter of the vas deferens. Also, a cell type designated as “mitochondrion-rich” was observed in the distal vas segment. The structure of the small mitochondria in such cells, however, did not conform to the description of mitochondria in similar cells found in the human (Hoffer, '76). Intraepithelial macrophages containing residual accumulations which often resembled spermatozoan remnants in advanced stages of dissolution were present in all segments of the rat vas deferens, confirming in this species a spermiophagic role for such cells.
    Additional Material: 20 Ill.
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  • 100
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    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 194 (1979), S. 187-199 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: This study investigates the development of the vascular system of the puppy kidney (1-21 days after birth) after preparing casts of the renal vessels. At two days, the intrarenal vascular system distal to the afferent arteriole is strikingly different than that of the adult. The glomeruli of the outer cortex consist of a single dilated vessel while those of the mid and inner cortex possess an increasingly larger number of capillary loops. The efferent arterioles vary greatly in appearance from outer to inner cortex. Those in the nephrogenic zone are characteristically short and narrow and join a larger venous vessel termined a sinusoidal capillary. An efferent system somewhat similar to that of the adult is seen in the mid and inner cortex. One of the most obvious differences noted between the puppy and adult kidney is the relative lack of peritubular capillary networks throughout the cortex of the puppy kidney. The puppy possesses large, irregular vessels termed sinusoidal capillaries. The most rudimentary sinusoids are found in the outer cortex with more mature vessels in the inner cortex. The vascular arrangement of the efferent arteriole and sinusoidal capillary appears as a post-glomerular shunt. Functionally, the shunt would direct blood flow away from the proximal tubule and thus could result in a low extraction ratio and Tm for secreted solutes.
    Additional Material: 23 Ill.
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