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Characterization of Inhibin/Activin Subunit: DISCUSSION(5)

In comparison to signals obtained from oocytes, we detected relatively low levels of both ZP3 and GDF9 mRNAs in human cumulus cells. While both ZP3 and GDF9 appear to be oocyte specific in mice, several investigators have observed ZP3 mRNA and/or protein in granulosa cells from other species, including humans. Thus, ZP3 mRNA detection in human granulosa-lutein cells is consistent with these earlier observations and demonstrates that human granulosa cells, like those from pigs and rabbits, can synthesize ZP3. buy yasmin online

Using RT-PCR on RNA recovered from individual human oocytes, the results presented here provide some novel insights into biosynthesis of inhibin/activin subunits, FS, and activin receptors at the mRNA level. Our results suggest that oocytes could respond to an activin signal emanating from surrounding granulosa cells but that oocytes themselves do not make or secrete inhibin or activin. Taken together with the observation that treatment of immature rat follicles with activin and FSH stimulated oocytes to produce a follicle-organizing activity in vitro, our results suggest that granulosa cells modulate some aspects of oocyte function by secreting activin, which in turn regulates granulosa cell and follicular development and maturation. The biochemical nature of these activin-responsive signals therefore merits further investigation.