Follicle-stimulating hormone treatment reverses the effect of hypophysectomy on cell proliferation in the chicken embryo ovary

The present study evaluated the effect of FSH treatment on ovarian cell proliferation in the hypophysectomized chicken embryo. Hypophysectomy (Hx) was performed by the partial decapitation technique. Two series of experiments were performed: (a) Hx embryos were treated at 8 days of development with recombinant human FSH (rhFSH) and evaluated at 9 days by measuring BrdU incorporation; (b) Hx embryos were injected with rhFSH and rhCG at 9 days of development and the proliferation rate was measured at 13 days. The presence of mRNA for FSHR and LHR in the ovary of control and Hx embryos was demonstrated by RT-PCR analysis. There was a decrease in the percentage of BrdU labeled cells in the absence of hypophysis at 9 and 13 days of incubation. The decrease was reversed with rhFSH treatment. This effect was observed in the ovarian surface epithelium and the somatic cells of the cortex and the medulla in the 9-day-old embryo. Moreover, the number of somatic, steroidogenic, and germ cells was reduced at 13 days of incubation in the Hx embryo; when treated with rhFSH the number of cells increased to the level of controls. In another experiment, ovaries of 9-day-old chicken embryos were organ cultured for 48 h in a serum-free medium with rhFSH and rhCG separately. The proliferation index was incremented by rhFSH compared to control and rhCG-treated embryos. Therefore, FSH stimulates somatic cell proliferation in the chicken embryo ovary as early as 9 days of development.