Archive for the 'Reproductive Function' Category

28 Nov

Gonadotropins and Reproductive Function: DISCUSSION(3)

These findings together with those on plasma GtH changes, discussed above, confirm in this anuran the role of GtH in vitellogenesis. Although it is not yet known whether or not FSH and LH have separate functions in amphibians, it is clear that GtH induces ovarian steroid production. The results reported here are in agreement with […]

27 Nov

Gonadotropins and Reproductive Function: DISCUSSION(2)

Seasonal fluctuations of plasma FSH and LH in female frogs are consistent with peak values of FSH at the beginning of the breeding period, when levels of E2 and VTG were also found to be high; in contrast, high LH plasma levels, coupled with the GSI trend, were evidenced during recrudescence and winter stasis. The […]

26 Nov

Gonadotropins and Reproductive Function: DISCUSSION(1)

The present study throws new light on the role played by GtH in amphibian reproduction. In the wild population of R. esculenta, LH plasma changes in males showed high values during the autumn-winter months and during the mating period, when high androgen levels were also found. According to Licht et al. and Itoh et al. […]

25 Nov

Gonadotropins and Reproductive Function: RESULTS(4)

In Vitro Effects of Bullfrog FSH and LH on Hepatic VTG Synthesis The effects of bullfrog GtHs on in vitro hepatic VTG synthesis were assessed in the main phases of the annual reproductive cycle of female frogs, the experiments on dose-response effects having been previously performed (data not shown). Figure 5a shows that during breeding period, […]

24 Nov

Gonadotropins and Reproductive Function: RESULTS(3)

Figure 4a shows the effects of 10 ng/ml of both FSH and LH in inducing E2 and progesterone changes in the CM of frog follicles harvested during the postreproductive summer phase. The follicles were also incubated in presence of HPH as positive control. Regarding E2 production, bullfrog FSH induced a significant (p < 0.01) increase […]

23 Nov

Gonadotropins and Reproductive Function: RESULTS(2)

Ovarian growth started in September and lasted until November; ovary weight remained high during the winter months and early spring, when spawning occurs, and then sharply decreased. Plasma VTG significantly (p < 0.005) increased from baseline levels obtained during the summer months to 0.85 ± 0.30mg/ml in October. A much greater plasma VTG increase, consisting […]

22 Nov

Gonadotropins and Reproductive Function: RESULTS(1)

Plasma GtHs and Androgen Changes in Males In Figure 2, plasma changes in FSH and LH during the male reproductive seasonal cycle are depicted. The levels of both FSH and LH were about 2-4 ng/ml from May until October, when LH titers significantly (p < 0.05) increased to 7.06 ±3.1 ng/ml. The levels of LH […]

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