Sites of estrogen receptor and aromatase expression in the chicken embryo

Abstract

Estrogens have been implicated in sexual differentiation of both the gonads and the genitalia of birds. In chicken embryos, the gonads are steroidogenically active from an early age, and the aromatase gene, (cAROM), necessary for estrogen synthesis, is expressed only in females at the time of gonadal sex differentiation. However, no studies have directly demonstrated the distribution of estrogen receptor (cER) transcripts or proteins in the embryonic avian reproductive system. Whole-mount in situ hybridization and immunohistochemistry were used here to identify sites of estrogen receptor expression in the embryonic chicken urogenital system. Estrogen receptor mRNA was observed in both male a..