The Sow Endometrium at Different Stages of the Oestrous Cycle: Immunohistochemical Study on the Distribution of SWC3-Expressing Cells (Granulocytes, Monocytes and Macrophages)

Uterine samples from sows taken immediately after slaughter at late di-oestrus, pro-oestrus, oestrus, early di-oestrus and di-oestrus, were analysed by immunohistochemistry with an avidin-biotin-peroxidase method using a monoclonal antibody (anti-SWC3) to granulocyte, monocyte and macrophage populations. The endometrium was then examined by light microscopy. In the surface and glandular epithelium, the largest numbers of SWC3-expressing cells (P ≤ 0.01 and P ≤ 0.05) were found at oestrus, and at pro-oestrus and oestrus, respectively. The numbers of SWC3-expressing cells in the epithelium were positively correlated with the plasma levels of oestradiol-17β. In the connective tissue of the subepithelial and glandular layers, no significant effect of the oestrous cycle stage was found on the number of SWC3-expressing cells. The present study showed a variation in the distribution of SWC3-expressing cells in the sow endometrium, especially in the surface and glandular epithelium, during different stages of the oestrous cycle.