PARENT SESSION
Gonadotropins and Pituitary

CHANGES IN SOMATIC CELL NUMBER IN THE OVARY OF HYPOPHYSECTOMIZED CHICK EMBRYOS AND WITH ADENOHYPOPHYSEAL GRAFTS.

Méndez, Carmen¹, Ramírez, Marcela², Carrasco, Erika¹, Alvarez, Inés¹, Pedernera, Enrique¹, ^{1 2}

ABSTRACT- This study aimed to evaluate changes in the number of somatic cell subpopulations in the ovary of chick embryos hypophysectomized by partial decapitation. Hypophysectomy was done at 44-46 h of incubation by a surgical procedure at mesencephalic level. The hypophysectomy effect was reverted by grafting two adenohypophysis on the chorioallantoic blood vessels at 9 days of incubation. Donors were 10-day-old chick embryos. The total number of somatic cells was counted after trypsin dissociation of the left ovary in 8-, 9-, 10-, 11-, 13-, and 14-day-old chick embryos. The number of somatic cells increased from 0.18 ± 0.04 10⁶cells/ovary (n = 10) at 8 days of incubation to 3.02 ± 0.72 10⁶cells/ovary (n = 9) at 14 days of development. In the hypophysectomized embryos, no difference in somatic cell number was registered in 8-, 9-, and 10-day-old embryos, but it was significantly reduced at 11, 13, and 14 days of development. Typical steroidogenic cells could be identified in the ovary of 14-day-old chick embryo, the number of this cellular type was reduced 43% after hypophysectomy. The embryos that received adenohypophyseal grafts at day 9 of incubation displayed similar values to controls in both somatic cell subpopulations at 14 days of development. These results demonstrate that adenohypophysis is one of the factors regulating the number of somatic cells in the ovary and influencing the amount of typical steroidogenic cells, probably through the effect of gonadotropic hormones on ovarian cell proliferation and differentiation. This effect is observed from 11 days onwards in the chick embryo development. Supported by DGAPA IN212900 and CONACYT 34996-N.

KEY WORDS: adenohypophysis graft, chicken embryo, hypophysectomy, ovary