Evidence for estrogen receptor expression in germ cell and somatic cell subpopulations in the ovary of the newly hatched chicken

Abstract.

Estrogens are involved in the gonadal morphogenesis of vertebrates, and almost all hormonal effects of 17ß-estradiol are mediated through specific receptors. At the time of sexual differentiation in the chicken, or even before, there is evidence of the presence of estrogen receptors and the secretion of 17ß-estradiol. However, no information is available regarding the cellular types that express the estrogen receptor in the immature chick ovary. The present study analyzes estrogen receptor expression in germ and somatic cells of the ovary in the newly hatched chicken. Highly purified cell subpopulations of germ and somatic cells were evaluated for specific 17ß-estradiol nuclear binding. In addition, the estrogen receptor was localized at the ultrastructural level by the immunogold technique. Finally, reverse transcription and polymerase chain reaction procedures detected a steady-state level of mRNA for the estrogen receptor. Somatic cells including typical steroidogenic cells showed specific 17ß-estradiol nuclear binding, displayed the estrogen receptor, and possessed estrogen receptor transcripts. The same result was observed in primary oocytes, together with the ultrastructural localization of estrogen receptor in extended chromatin filaments. Our experimental data support the hypothesis that estrogens are involved in the function of somatic and germ cells subpopulations in the immature chicken ovary.