Relationship between seasonal plasma estradiol-17 beta and testosterone levels and in vitro production by ovarian follicles of amago salmon (Oncorhynchus rhodurus).
01 Sep 1983-Biology of Reproduction (Society for the Study of Reproduction)-Vol. 29, Iss: 2, pp 301-309
TL;DR: The seasonal pattern of plasma testosterone levels lagged behind and followed that of estradiol-17 beta during vitellogenesis, but levels remained high in mature and ovulated fish, and GSI values showed a linear increase, and reached a peak in October.
Abstract: Plasma estradiol-17 beta and testosterone levels were assessed by radioimmunoassay during the sexual maturation of female amago salmon (Oncorhynchus rhodurus). Estradiol-17 beta levels gradually increased during vitellogenesis (June to September), reached a peak in September (about 16 ng/ml) and rapidly decreased in mature and ovulated fish (about 3-4 ng/ml) in October. The seasonal pattern of plasma testosterone levels lagged behind and followed that of estradiol-17 beta during vitellogenesis, but levels remained high in mature and ovulated fish (90-110 ng/ml). Estradiol-17 beta levels and the gonadosomatic index (GSI) values correlated well during vitellogenesis: GSI values showed a linear increase, and reached a peak (29.9 +/- 1.4) in October. Values were extremely low in ovulated fish (1.2 +/- 0.2). In vitro production of estradiol-17 beta and testosterone by ovarian follicles in response to partially purified chinook salmon gonadotropin (SG-G100) was examined monthly using 18-h incubations. Throughout the vitellogenic period SG-G100 stimulated both estradiol-17 beta and testosterone production: the steroidogenic response of follicles increased from June (about 2 ng/ml estradiol-17 beta; 0.1 ng/ml testosterone) to September (about 10 and 14 ng/ml, respectively). In October full-grown immature follicles which could be induced to mature in vitro by hormone treatment produced large amounts of testosterone (about 130 ng/ml) but not estradiol-17 beta. Postovulatory follicles also produced testosterone but the values were low (10 ng/ml) compared with full-grown immature follicles. Very low levels of estradiol-17 beta were produced by postovulatory follicles.(ABSTRACT TRUNCATED AT 250 WORDS)
Citations
More filters
TL;DR: Ultrastructural aspects of the ontogeny and differentiation of ray-finned fish ovarian follicles are studied in the context of fish oocyte ontogenesis and differentiation.
Abstract: p. 350. Le Menn, Derda J, Babin P. Ultrastructural aspects of the ontogeny and differentiation of ray-finned fish ovarian follicles. In: Babin PJ, Cerda JC, Lubzens E (eds). The Fish Oocyte: From Basic Studies to Biotechnological Applications. Springer, Dordrecht, The Netherlands. 2007;
64 citations
Cites background or methods from "Relationship between seasonal plasm..."
...Their plasma steroid levels and concentrations of in vitro production are very high (Kagawa et al. 1983; Young et al. 1983b), indicating reduction of the follicle number for in vitro incubation and easy detection of steroid concentration in the plasma and incubation medium....
[...]
...The two different cell layers (especially the granulosa layer) are then washed with TBSS to remove the yolk....
[...]
...Plasma E2, testosterone, and DHP in two salmonids (white-spotted char, Salvelinus leucomaenis, and amago salmon Oncorhynchus rhodurus) were measured by radioimmunoassay (Kagawa et al. 1981, 1983; Young et al. 1983a)....
[...]
...Their ovaries are quickly removed and kept in ice-cold HEPES-NaOH buffered (pH 7.5) trout balanced salt solution (TBSS) (Kagawa et al. 1982, 1983)....
[...]
...Their plasma steroid levels and concentrations of in vitro production are very high (Kagawa et al. 1983; Young et al. 1983b), indicating reduction of the follicle number for in vitro incubation and easy detection of steroid concentration in the plasma and incubation medium....
[...]
TL;DR: Under stimulation of fish pituitary extract (FPE), as a source of gonadotropin, in vitro production of E(2) and T by the vitellogenic follicles was shown to be highest compared to their production rate in other stages, while the postvitellogenesis follicles recorded the highest rate of DHP synthesis.
62 citations
01 Jan 1987
TL;DR: The regulation of the corpus luteum activity in mammals is complex and not completely understood, especially as the mammalian corpus lUTEum may secrete hormones other than steroids (polypeptide hormones, prostaglandins), the roles of which remain to some extent to be determined.
Abstract: Corpora lutea are ephemeral endocrine glands occurring in all vertebrate groups. These structures develop in the ovaries after ovulation, from the membranes of postovulatory follicles. The processes of luteogenesis, luteal maintenance and luteolysis have been studied extensively in mammals. Luteinization of the cells lining the follicular cavity is accompanied by a striking increase in progesterone secretion. Progesterone is the hormone required for the establishment of pregnancy, and the main function of the mammalian corpus luteum is to synthesize and secrete this steroid. Autonomy of progesterone secretion is short-lived in mammals, and the ability of the corpus luteum to maintain progesterone secretion depends on the action of permissive and/or stimulatory factors. Regression of progesterone secretion results from the luteolytic action of other factors. The regulation of the corpus luteum activity in mammals is complex and not completely understood, especially as the mammalian corpus luteum may secrete hormones other than steroids (polypeptide hormones, prostaglandins), the roles of which remain to some extent to be determined.
61 citations
TL;DR: The effects of mammalian pituitary and placental hormones and dibutyryl cyclic AMP (cAMP) on the production of estradiol-17 beta and 17 alpha, 20 beta-dihydroxy-4-pregnen-3-one by amago salmon ovarian follicles in vitro were compared with partially purified chum salmon gonadotropin (SGA).
59 citations
TL;DR: There appears to be a relationship between the delayed initial peaks of the steroid hormones measured, oocyte growth arrestment, and longer-lived postovulatory follicles in mouthbrooding female tilapia.
59 citations