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

Estrogens are involved in the gonadal morphogenesis of vertebrates, and alm ost all hormonal effects of 17 beta-estradiol are mediated through specific receptors. At the time of sexual differentiation in the chicken, or even b efore, there is evidence of the presence of estrogen receptors and the secr etion of 17 beta-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 c ell subpopulations of germ and somatic cells were evaluated for specific 17 beta-estradiol nuclear binding. In addition, the estrogen receptor was loc alized at the ultrastructural level by the immunogold technique. Finally, r everse transcription and polymerase chain reaction procedures detected a st eady-state level of mRNA for the estrogen receptor. Somatic cells including typical steroidogenic cells showed specific 17 beta-estradiol nuclear bind ing, displayed the estrogen receptor, and possessed estrogen receptor trans cripts. The same result was observed in primary oocytes, together with the ultrastructural localization of estrogen receptor in extended chromatin fil aments. Our experimental data support the hypothesis that estrogens are inv olved ire the function of somatic and germ cells subpopulations in the imma ture chicken ovary.