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Research article2003Peer reviewed

Immunohistochemical studies on oestrogen receptor alpha (ER alpha) and the proliferative marker Ki-67 in the sow uterus at different stages of the oestrous cycle

Sukjumlong S, Kaeoket K, Dalin AM, Persson E

Abstract

In order to better understand physiological changes during the different stages of the oestrous cycle, immunohistochemistry was used in the present study to investigate the distribution of oestrogen receptor alpha (ERalpha ) as well as the proliferative marker Ki-67, in the sow uterus during the oestrous cycle. Uterine samples were collected from multiparous sows with normal reproductive performance at selected stages of the oestrous cycle: at late dioestrus (d 17), prooestrus (d 19), oestrous (d 1), early dioestrus (d 4) and dioestrus (d 11-12), respectively. The tissue samples were fixed in 10% formaldehyde, embedded in paraffin and subjected to immunohistochemistry using monoclonal antibodies against ERalpha (C-311) and Ki-67 (MM-1). In general, the immunostaining of both ERalpha and Ki-67 was confined to nuclei of the target cells. Variations were seen, not only at the different stages of the oestrous cycle, but also in the different tissue compartments of the uterus. In the epithelia, the strongest ERalpha staining and highest amount of positive Ki-67 cells were found at early dioestrus. In the myometrium, the highest levels of staining of both ERalpha and Ki-67 positive cells were found at pro-oestrus and oestrus. For the proliferative marker, Ki-67, no positive cells were found at dioestrus and late dioestrus in the epithelium and myometrium. In the connective tissue stroma (subepithelial layer), the highest number of ERalpha positive cells were found at oestrus, which was significantly different compared with other stages (pless than or equal to0.05), whereas the levels of Ki-67 positive cells were relatively low and did not differ between the stages examined. Significant correlations between the number of ERalpha positive cells in the stroma and Ki-67 positive cells in the epithelia were observed. This suggests indirect regulatory mechanisms on epithelial proliferation via ERalpha in the stroma. In conclusion, these findings in the sow uterus show that the presence of ERalpha as well as Ki-67 protein varies not only between different stages of the oestrous cycle but also between different tissue compartments of the uterus. These findings indicate various regulatory mechanisms and stress the importance of localising ERalpha and proliferating cells in different uterine tissues

Keywords

swine; reproduction; uterus; oestrogen receptor; proliferation; immunohistochemistry

Published in

Reproduction in Domestic Animals
2003, Volume: 38, number: 1, pages: 5-12
Publisher: BLACKWELL VERLAG GMBH