J. Takeyama et al., Expression and cellular localization of estrogen receptors alpha and beta in the human fetus, J CLIN END, 86(5), 2001, pp. 2258-2262
Estrogens exert various biological effects by acting through their native r
eceptors, two of which have been identified to date: estrogen receptors alp
ha (ER alpha) and beta (ER beta). In this study we examined the expression
and cellular localization of ER alpha and ER beta in various human fetal ti
ssues by semiquantitative RT-PCR (13 and 20 gestational weeks) and immunohi
stochemistry (13, 20, and 38 gestational weeks), respectively, to study the
possible effects of estrogens on human fetal tissues during development. R
elatively high levels of ER beta expression were detected in various human
fetal tissues, whereas those tissues expressing ER beta had markedly lower
levels of ER alpha expression. ER beta messenger ribonucleic acid expressio
n was especially high in the adrenal gland. ER beta -immunoreactive protein
was localized to the definitive zone, but not in the fetal zone, of the ad
renal cortex. Although low levels of ER beta messenger ribonucleic acid wer
e present in the brain, heart, lung, and kidney, ER beta immunoreactivity w
as not detected in these tissues. These results suggest that the effects of
estrogens in these tissues are predominantly mediated through ER beta. ER
beta immunoreactivity was detected in Sertoli cells and spermatogonia in th
e male reproductive tract and in germ cells in the fetal testis and epididy
mis. In the female reproductive tract, both ER alpha and ER beta were immun
opositive in epithelium of the oviduct. The results of the present study ha
ve demonstrated the possible sites for estrogenic action in the human fetus
: and suggest that the effects of estrogen via ER beta may play important r
oles in human fetal development, especially in the definitive zone of the a
drenal cortex, and in the reproductive tissues of the developing fetus.