Figure 3.

Equine endometria immunostaining for β-defensin (a), indoleamine 2,3-dioxygenase 1 (IDO 1) (b) and Toll-like receptor 4 (TLR 4) (c,d). Positive staining is shown by a brown color reaction; 3,3′ diaminobenzidin is used as chromogen. (a) In the healthy endometrium, β-defensin is mainly expressed in the cytoplasm of epithelial cells lining the luminal surface (black arrowhead) and glandular ducts (white arrowheads). Bar = 30 µm; (b) IDO 1 immunostaining is predominantly observed in glandular epithelial cells (gray arrowheads). Bar = 50 µm; (c–d) Staining for TLR 4 markedly differs between individual mares. Positive cells include epithelial cells of the luminal surface (c: black arrowhead), glandular ducts (c: white arrowhead), secretory portions of glands (c: gray arrowhead), stromal cells (c: asterisk), and/or mast cells (d: black arrows). Bars = 20 µm.