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  • 2005-2009
  • 1990-1994  (1)
  • 1975-1979  (1)
  • Cell & Developmental Biology  (2)
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 36 (1993), S. 331-337 
    ISSN: 1040-452X
    Keywords: Ovulation ; Meiotic maturation ; Vixens ; Polar fox ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A total of 15 blue fox vixens aged 1-6 years were mated, 12 once on the first day of estrus and three a second time 48 hr after the first mating, and were killed 4 hr to 8 days following mating. Ova were collected from the oviducts, evaluated by stereomicroscopy, and studied by transmission (TEM; N = 49, 12 vixens) or scanning (SEM, N = 11, three vixens) electron microscopy. At 0-3 days after ovulation, the ova had not cleaved and were at different stages of meiotic maturation. In about one-half of these ova, representing all stages of meiotic maturation, a decondensing sperm head without nuclear envelope or a small pronucleus with partial nuclear envelope was observed. No clear relationship was found between maternal meiotic stage and the stage of paternal pronucleus formation. Sperm tails were never identified in the ooplasm. Cortical granules were released after sperm penetration at early stages of meiotic maturation. Thus the block against polyspermic penetration was activated during maturation of the oocyte. The first two-cell stage appeared 4 days after ovulation (3 days after mating), the first four-cell stage the following day (day 5), and the first eight-cell stage 6 days after ovulation (5 days after mating). In a single vixen mated late (7 days postovulation) two- to four-cell stages appeared the following day (day 8). This indicates that the time required for the first cleavage division decreases with increasing interval from ovulation to mating. The development of a functional nucleolus with fibrillar centers and fibrillar and granular components at the eight-cell stage indicates activation of embryonic RNA synthesis in fox embryos at the six- to eight-cell stage, suggesting that the embryonic genome is activated at this stage. © 1993 Wiley-Liss, Inc.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 95 (1978), S. 287-294 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The potent tumor promoter tetradecanoyl phorbol acetate (TPA) induces early changes in ion movements analogous to those induced by prostaglandins E1 and F2α. Among the earliest changes induced by TPA is a significant increase in 32Pi incorporation within 15 minutes incubation of TPA (10-8-10-6 M) with post-confluent Swiss 3T3 mouse embryonic fibroblasts. Similarly, the active phorbol ester homolog 4-;β-;OH phorbol didecanoate but not the inactive stereoisomeric 4-β-OH phorbol didecanoate stimulated 32Pi incorporation. Also, TPA at the above concentrations stimulated 86Rb+ influx shortly after administration. Both fluxes were ouabain-sensitive in accord with the idea that an early effect of TPA is to alter (Na+ + K+)-ATPase activity. Further, prostaglandin E1 (10-7-10-6 M) and prostaglandin F2α (3 × 10-9-10-7 M) caused a similar stimulation of 86Rb+ and 32Pi uptake. The finding that water-soluble prostaglandin F2α also exhibited stimulatory effects indicated that those hormone-induced responses are not mediated by solvent interactions. The similar responses of phorbol esters and prostaglandin derivatives suggests that phorbol esters and prostaglandin derivatives may act at common membrane sitesThe finding that stimulatory effects were observed at discrete times in the logarithmic phase of growth suggests that the activation of membrane receptors may be cell-cycle dependent.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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