Large antral follicles grow in waves in the ewe, with each wave triggered by a peak in serum FSH concentrations. In this study, our objectives were to determine if the slope of the rise in the FSH peak affects the ability of the peak to trigger wave emergence (experiment 1), and whether increasing serum FSH concentrations and holding them at peak concentrations would provide a stimulus for constant emergence of large antral follicles (experiment 2). In experiment 1, cyclic ewes received ovine FSH (n = 6; 0.1 μg/kg, s.c.) or vehicle (n = 6; control) every 6 h for 42 h. This treatment created a peak in serum FSH concentrations (P < 0.05) during the early growth phase of the first follicular wave of the interovulatory interval and enhanced the growth of follicles in that wave (P < 0.05), but did not trigger emergence of a follicular wave. In experiment 2, cyclic ewes were infused constantly with oFSH (1.98 μg/h; n = 6) or vehicle (control; n = 6) for 60 h starting at the time of the second endogenously driven FSH peak of the interovulatory interval. Infusion of oFSH resulted in a super-stimulatory effect, with a peak in the mean number of large follicles (≥5 mm) on Day 2 after the start of FSH infusion (13 ± 1.2 large follicles per ewe, 1.8 ± 0.2 in control ewes; P < 0.001). In conclusion, exposing early growing antral follicles in a wave to a gradual increase in serum concentrations of FSH enhanced their growth, but did not trigger the expected new follicular wave, and infusion of a dose of oFSH within the physiological range caused a super-ovulatory response in cyclic ewes.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.
Vol. 83 • No. 4