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N Dekel

Publications and source records attributed to N Dekel.

60 records · Page 4Linked to original sources
PubMed1977

Follicular development during late human pregnancy.

In contrast to the accepted view of ovarian quiescence during pregnancy, the ovaries of preparturient women are covered with a dense population of small superficial follicles. In this study we have measured the follicular size and status of the oocytes and cumulus oophorus in 298 follicles from the ovaries of 30 women. The samples were taken at cesarean section and were examined with Nomarski differential interference microscopy. No oocyte was recovered from 50% of the follicles; 79% of the recovered oocytes and 78% of their cumuli were degenerative. Degeneration was correlated with appearance of phagocytes in the follicular fluid. These findings suggest that the endocrine status of gestation does not prevent early follicular development, but induces premature atresia.

Female↗
PubMed1976

Effects of gonadotrophins on the cumulus oophorus of isolated rat Graafian follicles.

Graafian follicles were extirpated before the endogenous LH surge on the day prior to ovulation from PMS-injected immature rats. They were incubated in chemically defined medium in presence or absence of gonadotrophins for 4-10 h. After incubation the oocyte-cumulus complexes were recovered from the follicles and one group inspected by Nomarski interference contrast microscopy and one group was placed in saline containing hyaluronidase. In hormone-free medium both the oocyte and the cumulus cells remained morphologically unchanged: a dictyate oocyte surrounded by a compact mass of cumulus cells. Hyaluronidase did not detach cells from the cumulus structure. However, in presence of LH or FSH morphological changes developed in both cell types: the oocyte resumed meiosis as revealed by germinal vesicle breakdown and polar body formation; the cumulus structure became dispersed and embedded in a viscous matrix. The individual cumulus cells displayed pseudopodia-like processes of the cell surface. Treatment with hyaluronidase resulted in detachment of cells from the cumulus. The effects of LH described on the oocyte and cumulus cells were unimpaired in presence of cyanoketone or aminoglutethimide although these agents blocked the follicular relase of progesterone, estradiol and androstenedione as revealed by RIA. The results indicate that a close functional relationship exists between the two cell types of the cumulus oophorus, the oocyte and the cumulus granulosa cells. Both cell types are affected directly or indirectly by gonadotrophins and characteristical morphological changes develop synchronously in both cell types.

Aminoglutethimide↗
PubMed1976

Effect of luteinizing hormone on respiration of the preovulatory cumulus oophorus of the rat.

The effect of luteinizing hormone (LH) on the respiration of isolated cumulus cell complexes (the oocyte surrounded by cumulus granulosa cells) obtained from immature Sprague-Dawley rats injected with 10 IU pregnant mare's serum gonadotropin on day 30 was investigated. The cell complexes were isolated from preovulatory follicles of rats killed at specific time intervals on the day preceding ovulation, i.e., on day 32. The samples were incubated in Eagle's tissue culture medium. Oxygen uptake was recorded either with the Cartesian diver technique or with a recently described microspectrophotometric technique using hemoglobin as an indicator. Exposure to exogenous bovine LH in vitro or in vivo or to endogenous LH, i.e., the preovulatory LH-surge, resulted in a marked decrease in respiratory activity of the cumulus cell complex, as revealed by both techniques. The cumuli exposed to LH showed an oxygen uptake of approximately 40-65% of the control cumuli. The results suggest that LH has a direct effect on this cell complex resulting in a decreased oxidative metabolism.

Animals↗