Estrogen receptor protein and mRNA expression in the ovary of sheep

Abstract

Using immunohistochemistry and in situ hybridization, we attempted to identify the estrogen receptor (ER) protein and messenger RNA (mRNA) in sheep ovaries during the follicular phase of the estrous cycle. Monoclonal anti‐ER antibodies H222 and 1D5 were used for localizing estrogen receptor on ovarian cryo‐sections. Labeling for ER was found over the nuclei of surface epithelium, interstitial tissue, and granulosa cells of small as well as large ovarian follicles. In the preantral and small antral follicles, intense nuclear ER labeling was observed in mural granulosa cells and particularly in cumulus/granulosa cells surrounding the oocyte. In the large healthy looking follicles, greater diversity in labeling for ER was observed, which is characterized by mixed populations of granulosa cells expressing positive and more or less negative nuclear labeling. Such a pattern of labeling was particularly evident in follicles showing the signs of atresia. Generally, more intense nuclear staining was localized in granulosa cells proximal to basal membrane. In situ hybridization studies revealed the presence of ER mRNA in ovarian tissue. Autoradiographic visualization localized ER mRNA expression over the granulosa cells of healthy follicles of all sizes. Level of hybridization signal was comparable in mural and cumulus granulosa cells. In atretic follicles, the level of hybridization signal in granulosa cells was comparable to that of healthy follicles. A relatively weaker level of labeling was observed in granulosa cells dispersed in follicular antrum in follicles with advanced atretic lesions. Theca cells expressed a lower level of labeling than granulosa cells. Specificity of labeling for both ER protein and mRNA in ovary was proved by parallel probing the ovine uterus. Ovine ER recognition by both H222 and 1D5 antibodies was also proved by immunoblotting. These studies demonstrate the presence of the estrogen receptor and its messenger RNA in the sheep ovary and suggest an autocrine/paracrine role of estradiol and its receptor in the regulation of ovarian follicle development in sheep. Mol. Reprod. Dev. 48:53–62, 1997. © 1997 Wiley‐Liss, Inc.

Immunohistochemical localization of estrogen receptor-α in sex ducts and gonads of newborn piglets

“…The immunohistochemical localization of ER-α in piglet ovaries agrees with data on rodents (Sar and Welsch 1999;Nielsen et al 2000). In sheep ovaries, however, the ER-α immunohistochemical localization during the follicular phase was not restricted to the surface epithelium and stroma but was also recognized in granulosa cells of small and large follicles (Tomanek et al 1997). The data on piglets and sheep ovaries are obtained by using the same primary estrogen receptor antibody and the reason for the discrepancy in ER-α localization may be due to age and/or species differences rather than methodological variation.…”

Expression of Estrogen and Progesterone Receptors in the Bovine Ovary During Estrous Cycle and Pregnancy

“…In the ovary of domestic animals, ERa and ERb expression were demonstrated in bovine, sheep, and pig follicles (9,(18)(19)(20) and corpora lutea (20)(21)(22). The expression of PR was proved in humans (23,24), mouse (25) and rat (26), as well as in bovine and sheep follicular and luteal tissue (27)(28)(29)(30).…”

Distribution of Estrogen Receptor Alpha in the Dominant Follicles and Corpus Luteum at the Three Stages of Estrous Cycle in Japanese Black Cows

“…It is generally accepted that there exist two different estrogen receptor subtypes, namely estrogen receptor-alpha (ERα) and estrogen receptor-beta (ERβ). The presence of ERs in the ovaries of monkeys [4,7], sheep [19], humans [2,18], rats [14], cows [1,20] and pigs [15] has already been shown. Estrogen receptors play an important role in the maintenance of fertility.…”