During the oestrous cycle, inhibin serves two functions. Firstly, during the period of gradual follicle growth (approximately from 12.00h oestrus to 12.00h pro-oestrus), blood levels of FSH are kept at a low, basal level and within narrow limits, via specific short-term negative feedback of inhibin. Thus, inhibin may prevent undue recruitment of additional follicles. A personal experiment is reported which supports the presented concept of the physiological role of inhibin : injection on di-oestrous day-1 of antiserum against inhibin caused an endogenous peak of FSH after Sh and, a significantly increased ovulation rate at the next day of oestrus (section 3.2.1). Secondly, a rapid decrease of blood (OVP) levels of inhibin is seen after the (primary) surge of LH (and FSH) on pro-oestrous. Consequently, reduced suppression by inhibin of pituitary secretion of FSH takes place, which initiates the event of the second- or oestrous surge of FSH (not LH). Thus, during the peri-ovulatory phase the absence of inhibin induces the secondary surge of FSH and, therefore, inhibin is involved in recruitment of the follicles destined to ovulate at the next oestrus. In conclusion, during the oestrous cycle, inhibin is an important factor for follicle recruitment, for control of the balance between growth and atresia within a cohort of growing antral follicles and, thus, for regulation of ovulation rate.

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Erasmus University Rotterdam
J. Moll
hdl.handle.net/1765/51050
Erasmus MC: University Medical Center Rotterdam

Sander, H. J. (1988, November 7). Inhibin : role of inhibin in the endocrinology of reproduction of the female laboratory rat.. Retrieved from http://hdl.handle.net/1765/51050