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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 193 (1987), S. 225-239 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Pituitary glands of adult male lizards (Anolis carolinensis) were studied in an effort to monitor seasonal cytologic changes quantitatively. Cells were identified immunocytochemically and on the basis of ultrastructural characteristics.Electron micrographs of the anterior pars distalis (containing lactotropes, corticotropes, and gonadotropes) of lizards collected in spring and fall were analyzed morphometrically. Lactotropes are the most numerous cell type in this area and occupy the largest volume. They are closely followed by corticotropes. Neither kind of cell undergoes a marked seasonal change in number or size or in the percent of the analyzed volume they occupy. Morphometric and ultrastructural criteria indicate an increased level of activity in all three kinds of secretory cells in the spring, although changes are relatively modest in corticotropes and lactotropes.Gonadotropes occupy less than half the volume of either of the other secretory cells in the analyzed area, but undergo considerable seasonal modification. They are larger (〉 40%) and more numerous (20%) in the spring, and show an increase in biosynthetic organelles at this time. Although the density of secretion granules may be reduced in the enlarged spring gonadotropes, the number of granules per cell may not be altered seasonally.Seasonal changes in the three cell types analyzed are moderate in contrast to the cytologic modifications described in pituitary cells following castration or other experimental procedures. Necrotic cells appear to be a normal component of the pituitary gland of Anolis carolinensis throughout the year.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 213 (1992), S. 287-294 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Neurons in whole mount preparations of the frontal ganglion (FG) of the cockroach, Periplaneta americana, were mapped with the aid of cobalt chloride staining and silver intensification techniques. Eighty-six neurons were counted in the FG after staining with reduced methylene blue. The cell size ranged between 20 to 35 μm in diameter. Of the somata located in the FG, 44 were found to contribute their fibers to the nervus recurrens, 26 to the right frontal commissure, 28 to the left frontal commissure, and 6 to the nervus connectivus. In addition, a few neurons presumably from the tritocerebral region also contribute their fibers in the formation of nervus connectivus. The present study has helped delineate the neuronal connections of the FG with the brain and neuroendocrine system (corpora cardiaca and corpora allata). This information will be useful in facilitating the positioning of microelectrodes in our future electrophysiological experiments. © 1992 Wiley-Liss, Inc.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 150 (1976), S. 359-368 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Stereological analysis of the ultrastructural composition of the pulmonary alveolo-capillary region of mice living at sea level compared with that of the same species (Phyllotis darwini) genetically adapted to life at 4,660 m reveals a trend at high altitude towards a greater volume percentage of tissue components. On a weight-specific basis, non-circulating tissue occupies a significantly greater volume in high-altitude mice, but air space and capillary contents are not correspondingly greater. Since the arithmetic mean thickness of the tissue layers and of the air-blood barrier are the same in the two altitudinal groups, the average alveolus must have a smaller volume in the high-altitude mice.Epithelial, endothelial, and erythrocyte surface areas per gram body weight are significantly greater in the high-altitude mice.Nuclear counts indicate that the larger lungs of mice adapted to high altitude are due to larger Pneumocyte I and II and endothelial cells rather than to an increase in the number of these cells. Hematocrits measured within the pulmonary capillaries in the two altitudinal groups were equal.An heretofore unrecognized feature of possible adaptive value is the surface/volume ratio of erythrocytes, which is similar for erythrocytes in alveolar space of mice at low and high altitudes but within lung capillaries is 14.7% greater at high altitude.
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  • 4
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Ultrastructural studies on blood leukocytes of the channel catfish, Ictalurus punctatus, show the presence of heterophils (neutrophils), small lymphocytes, monocytes, and thrombocytes. Monocytes cannot always be distinguished from large lymphocytes. Cells resembling macrophages or transitional forms between monocytes and macrophages are occasionally seen. Blood eosinophils and basophils are not found. Thrombocytes and small lymphocytes are the most abundant leukocytes, while monocytes are the least frequently encountered leukocyte. Glycogen, present in all leukocytes, is most abundant in heterophils and least abundant in monocytes. Although monocytes are similar to heterophils in size and shape, a greater amount of rough endoplasmic reticulum, free ribosomes, and fewer granules are observed in monocytes. Heterophils possess oval or elongate granules, which often contain a crystalline or striated structure; small tubules which resemble smooth endoplasmic reticulum, and cristae which traverse the long axes of the mitochondria are frequently seen. Small lymphocytes are characterized by the presence of pseudopodia, many free ribosomes, numerous large mitochondria, dictyosomes (Golgi), and long profiles of rough endoplasmic reticulum. The dictyosomes are often associated with a large zone of exclusion. Bundles of microtubules are observed near the elongated ends of thrombocytes. Deep indentations of the plasmalemma, which give the appearance of vacuoles, are also seen in thrombocytes.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 200 (1989), S. 131-139 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The three-dimensional gross morphology of the pituitary gland of the garter snake (Thamnophis sirtalis) is presented. Hormone-producing cells of the pars distalis were localized immunocytochemically. Corticotropes and lactotropes occur in the anterior two-thirds of the gland; corticotropes are especially numerous in the area of the pars distalis nearest the median eminence, and lactotropes are most abundant medially. Somatotropes are restricted to the posterior one-third of the pars distalis. Gonadotropes and thyrotropes are scattered throughout the pars distalis and in favorable sections form a network of cells enclosing clusters of peptide-secreting cells.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 26 (1993), S. 205-213 
    ISSN: 0886-1544
    Keywords: septate junction ; α-actinin ; myosin II ; vinculin ; microfilament bundles ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cytoskeletal elements associated with the smooth septate junctions linking the midgut columnar cells of Manduca sexta larvae (Insecta, Lepidoptera) were characterized. Myosin subfragment 1 decoration and immunostaining for actin demonstrated that the filaments associated with the septate junctions were constituted of actin. Moreover, using a combination of immunochemical and immunolocalization techniques, evidence is presented that α-actinin, myosin II, and vinculin are localized close to the specialized plasma membranes. The insertion of microfilament bundles into submembranous F-actin/α-actinin/vinculin complexes, previously described in vertebrate junctions of adherens type, appears to be a more general organization, including the insect septate junction here examined. © 1993 Wiley-Liss, Inc.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 144 (1974), S. 85-117 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Anolis embryos have limb buds at the time eggs are laid and require about 39 days to complete development at 28°C. Rathke's pouch is present at five days, and the subdivisions of the adenohypophysis are differentiated by ten days after oviposition. The cells of the rostral half of the pars distalis (PD) are derived from the anterior face of Rathke's pouch; cells of the caudal half from the posterior face. Lateral lobe cells differentiate on the lateral margins of the developing caudal PD, and knob-like outgrowths of this tissue attach to the walls of the diencephalon to form the pars tuberalis (PT). Subsequently, the cells of the PT lose their connection with the PD and become a pair of flattened oblong plaques. They reach maximal size in midincubation, and are gradually invaded by nervous elements and incorporated into the walls of the hypothalamus. Electron micrographs demonstrate that the embryonic PT is secretory.Ultrastructurally the pars intermedia (PI) and PD are composed of parenchymous secretory cells in a framework of stellate cells. Stellate cells surround the lumen of Rathke's pouch and are connected laterally by complex junctions that exclude the secretory cells from the luminal surface. They extend in sheet-like processes among the secretory cells to the outer margin of the gland where they form a partial sheath within the basal lamina around the secretory tissue. As development proceeds, the lumen becomes subdivided and the resulting reduced lumina are recognizable as the forerunners of the follicles of the adult adenohypophysis.The cells of the PI are differentiated into secretory or stellate cells halfway through incubation. At this time only half of the cells of the PD can be so classified. Four of the five granulated cell types described in the adult are recognizable by mid-incubation; the fifth cell type (prolactin cell) becomes distinguishable within ten days thereafter, and at hatching appears to be actively synthesizing secretory products.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 28 (1991), S. 62-69 
    ISSN: 1040-452X
    Keywords: Rabbit spermatozoa ; Cytoskeletal proteins ; Immunolocalization ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Actin was localized in the four subacrosomal bulges (Camatini et al., Eur. J. Cell Biol. 45:276-281, 1987), which characterize the sperm head of rabbit spermatozoa (Phillips, J. Ultrastruct. Res. 38:591-604, 1972), and in the postacrosomal region (Welch and O'Rand, Dev. Biol. 109:411-417, 1985; Camatini et al., Eur. J. Cell Biol. 45:276-281, 1987). Specific antibodies and indirect immunogold labelling on testis Lowicryl K4M sections and spermatozoa cryosections were used to study the distribution of calmodulin and a spectrin-like protein. This protein was also present close to the shaping membranes of the head. The results presented suggest a membrane-cytoskeletal role of actin, spectrin, and calmodulin.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 32 (1992), S. 91-98 
    ISSN: 1040-452X
    Keywords: Transforming growth factor-β ; Embryogenesis ; Isoforms ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The TGF-β's are multifunctional, pleiotropic molecules with major effects in control of cellular migration, cellular proliferation, and elaboration of extracellular matrix. Thus far, five distinct isoforms of TGF-β have been described, each approximately 65-85% homologous and containing the characteristic 9 positionally conserved cysteine residues. Although the actions of the activated mature forms of the different isoforms on cells are qualitatively similar in most cases, there are a few examples of distinct activities. For example, TGF-β's 1 and 3, but not TGF-β2, inhibit the growth of large vessel endothelial cells, and TGF-β's 2 and 3, but not TGF-β1, inhibit the survival of cultured embryonic chick ciliary ganglionic neurons. In addition, selective targeting of the latent forms of the TGF-β's is suggested by the observation that latent TGF-β2 is the prominent isoform found in body fluids such as amniotic fluid, breast milk, and the aqueous and vitreous humor of the eye; it is noteworthy in this regard that TGF-β2 is unique among various isoforms in that it lacks a RGD integrin-binding sequence in its precursor. The most dramatic differences in the TGF-β isoforms are seen at the level of expression, where there is now a wealth of data demonstrating both spatially and temporally distinct expression of both the mRNAs and proteins in developing tissues, regenerating tissues, and in pathologic responses. Moreover, the post-transcriptional regulation of TGF-β expression by members of the steroid/retinoid family of nuclear receptors is also isoform-specific; thus, treatment of keratinocytes with retinoids induces secretion of TGF-β2, whereas treatment of breast cancer cells with gestodene, a synthetic progestin, induces secretion of TGF-β1. Recent characterization of the 5′ regulatory regions of the human TGF-β 1, 2, and 3 genes suggests that distinct features of the promoters, including the presence of TATAA boxes and transcription factor binding sites, form the basis for the observed differential transcription. © 1992 Wiley-Liss, Inc.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Microscopy Research and Technique 20 (1992), S. 232-250 
    ISSN: 1059-910X
    Keywords: Spermiogenesis ; Spermatozoa ; Mammals ; Cytoskeleton ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Identification of the cytoskeletal elements and their role in the formation as well as the maintenance of head membrane compartmentalization is a much debated issue in mammalian spermatozoa. Data which have emerged during the last ten years are summarized. Those which have converged in a common opinion, such as the distribution of actin in mammalian spermiogenesis, are distinguished from those which have to be confirmed, such as the role of actin related proteins and actin in mature spermatozoa.
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