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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 28 (1991), S. 136-142 
    ISSN: 1040-452X
    Keywords: Boar ; Bicarbonate ; cAMP ; Epididymis ; Maturation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The decrease in motility of porcine cauda epididymal sperm was less than that of caput epididymal sperm in the medium containing bicarbonate. This may be due to the difference of sensitivity of adenylate cyclase to bicarbonate between mature and immature sperm; activation of mature sperm enzyme by bicarbonate was higher than that of immature sperm. Nondialysable fraction of egg yolk prevented the decrease in motility of immature sperm in the presence of bicarbonate, but it was not effective for the motility of mature sperm under the same condition, because only bicarbonate is sufficient for the maintenance of its motility. In the absence of bicarbonate, both mature and immature sperm required egg yolk to maintain motility.The favorable effect of egg yolk on the motility is ascribed to the enhancement of intracellular cAMP level. Partial fractionation of egg yolk showed that water-insoluble lipoprotein fraction contains factor(s) which activates adenylate cyclase in sperm plasma membrane. This is the first report in which high molecular weight activator of the sperm enzyme was demonstrated.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 235 (1984), S. 623-633 
    ISSN: 1432-0878
    Keywords: Fetal porcine pituitary ; Corticotropin (ACTH) ; Growth hormone (GH) ; Prolactin (PRL) ; Thyrotropin (TSH) ; Gonadotropin (LH, FSH) ; Electron-microscopic immunocytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fetal porcine pituitary was investigated by means of ultrastructural immunocytochemistry (1) to identify the first cells synthesizing the adenohypophyseal hormones, (2) to follow their differentiation during fetal development, and (3) to compare their ultrastructural characteristics with those of mature adult cells. The first ACTH-cells, which produced and stored ACTH, β-LPH, β-MSH, and α- and β-endorphin in the same granules, were very numerous at day 34 and displayed a uniform morphology. At day 50 and thereafter, until the end of gestation, the ACTH-cells differed in their appearance probably reflecting various stages of differentiation of one cell type. The GH-cells gained rapidly ultrastructural features comparable to those of mature GH-cells. In contrast, in the case of PRL-cells, which appeared only at the end of the gestation period as immature elements containing very small secretory granules, the morphological maturation seemed to take place only after birth. The first cells synthesizing the glycoprotein hormones (LHα, LHβ, FSH and TSH) displayed ultrastructural features of immature cells. At day 50, their ultrastructural organization started to show a different pattern. At the end of gestation, the TSH-cells and the gonadotropic cells displayed the ultrastructural features of mature cells.
    Type of Medium: Electronic Resource
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