Adhesion molecule expression and infiltrating maternal leucocyte phenotypes during blastocyst implantation in the pig.

During the implantation period (days 14 to 30 post coitum) in Large White pigs substantial numbers of endometrial sub-epithelial leucocytes were observed from about day 18 p.c. These were predominantly MHC Class II+, CD45+ and reactive for an accessory cell determinant carried by polymorphs and macrophages. Maternal lymphocytes of the CD2+, CD4-, CD8-, and a gamma delta TcR+ subtype identified by the mAb 86D, were also present. Few CD4+, CD8+, or double-positive lymphocytes were seen. CD2-CD4-CD8- gamma delta TcR+ "Null" cells were seen in stroma adjacent to endometrial glands, as were CD2+ lymphocytes. There was no apparent up-regulation of CD18, VLA-4 or CD25. E-selectin could not be detected on endothelium within uterine tissues or on trophectoderm, nor was a ligand for L-selectin detectable. The luminal aspect of the uterine epithelium was strongly reactive with anti-CD15 mAb, which was specifically blocked by lacto-N-fucopentaose III, indicating the presence of the LewisX determinant.