Expression of αv, α4, α5 and β3 integrin subunits, fibronectin and vitronectin in goat peri-implantation

Integrins are glycoprotein heterodimers located in the cell membranes that stimulate intercellular adhesion and act as extracellular matrix (ECM) protein receptors. Although integrins have been detected in the implantation sites of various species, little is known about their participation in ruminant non-invasive placentation. The objective of this study was the detection of αv, α4, α5, β1 and β3 integrin subunits and of two of their ligands, fibronectin and vitronectin, to determine their participation in the caprine peri-implantation process. 21 post-coitum (pc), endometrial epithelium and trophoblastic cells showed an intense αv and β3 integrin subunits expression and moderate staining for α4 and α5. On Day 23 pc, integrin expression decreased noticeably and only a weak staining of α4 and β3 integrin subunits were observed. No β1 integrin subunit expression was detected on either of the days studied. Fibronectin (FN) expression in trophectodermic and endometrial epithelium was weak or moderate on the days studied while vitronectin (VN) expression in the same tissues was moderate or strong on Day 21 pc but decreased on Day 23 pc. These results suggest that αvβ3 integrin, α4 and α5 subunits, VN and FN are expressed in caprine endometrium and blastocyst and may play a role in the cascade of the implantation process.