ABSTRACT
Inhibin, a peptide first demonstrated in the Sertoli cells of seminiferous tubules, is under the control of FSH and can inhibit the secretion of FSH from the pars distalis. There is also evidence that granulosa cells may secrete a substance similar to inhibin. This action seems to be specific for inhibition of FSH release while LH secretions remains unchanged. Since then there is now extensive evidence for an inhibin-activin system in the regulation of ovarian folliculogenesis in birds. They are members of a conserved transforming growth factor b super family that play intragonadal roles via autocrine and paracrine actions. As yet, there is no evidence that activins act on the pituitary (Knight et al. 2005). There is also evidence for paracrine effect of a growth factor (GDF9) from the oocyte itself that also plays an important role in oocyte development-possibly during the yolk uptake phase (Johnson et al. 2005).
