ISSN:
1432-0878
Keywords:
Ovarian follicles
;
Oocyte maturation
;
Salmonid fishes
;
Steroidogenesis
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary Plasma estradiol-17β and progesterone profiles were correlated with morphological changes in ovarian follicles during the preovulatory and postovulatory periods in the white-spotted char, Salvelinus leucomaenis. Plasma estradiol levels were highest in September, and were followed by a sharp drop in October; they remained very low throughout the postovulatory period. There was a good correlation between plasma estradiol levels and the gonadosomatic index, thus suggesting that estradiol is responsible for the synthesis of vitellogenic proteins. Plasma progesterone levels were very low in August, began to rise in September and reached a peak soon after ovulation; progesterone remained high for several days after ovulation. A preovulatory rise in plasma progesterone levels was recorded, and this is discussed in relation to the induction of oocyte maturation. In the preovulatory follicles, neither granulosa cells nor special thecal cells (ST cells) showed Δ5, 3β-hydroxysteroid dehydrogenase (3β-HSD) activity. In the young postovulatory follicles, in contrast, the ST cells showed intense 3β-HSD activity with extensive agranular endoplasmic reticulum and numerous large mitochondria, while granulosa cells did not show 3β-HSD activity. These results strongly suggest that the ST cells are the major sites of progesterone synthesis during the postovulatory period.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00210347
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