Estrogen Receptor Alpha Localization in Thai Swamp Buffalo Oviduct during the Follicular and Luteal Phases

Estrogens are known to be an important modulator for regulation of the reproductive function in female mammals. The specific receptor of estrogens in the buffalo reproductive tract, particularly in the oviduct, has not been explored yet in the expression pattern. This study was, therefore, undertaken to investigate the localization of the estrogen receptor alpha (ER alpha) in the oviduct of Thai swamp buffalo at the follicular and late luteal phases of the estrous cycle. The oviducts were collected from swamp buffalo genital tracts at the local abattoir and separated into the uterotubal junction (UTJ), isthmus, ampulla and infundibulum. Tissue distribution of ER alpha was examined by immunohistochemical technique and the results showed that ER alpha was stained in nuclei of cells and can be detected in all compartments along the entire oviduct at both follicular and late luteal phases. The intensity of immunostaining and proportion of ER alpha positive cells in the epithelium and the subepithelial connective tissue of UJT and the isthmus was significantly higher (p<0.05) in the follicular compared to the luteal phase. A higher ER alpha expression during the follicular phase was also found in the ampulla and infundibulum. However, in these parts of the oviduct the increase in ER alpha expression was not statistically significant.