Cyclic modulation of epithelial glycosylation in human and baboon (Papio anubis) endometrium demonstrated by the binding of the agglutinin from Dolichos biflorus

Glycoconjugate expression in endometrial epithelium varies in a cycle- dependent manner in many species and is probably fundamental to the establishment of a receptive uterine environment for the implanting embryo. We have examined the distribution of N-acetyl galactosamine (GalNAc)- containing sequences bound by Dolichos biflorus agglutinin (DBA) in the cycling endometrium of the human and baboon (Papio anubis). In the human, DBA binding was absent in the proliferative and early secretory phases of the cycle, increasing thereafter both in glands and on the surface epithelium. In contrast, DBA binding in the baboon was maximal in the proliferative phase, diminishing to almost indistinguishable levels in the late secretory phase. Treatment of early to mid-secretory-phase baboons with the antiprogestin Onapristone caused staining to revert to the proliferative-phase pattern, confirming the importance of progesterone in the decrease in DBA staining. Investigations with other GalNAc-binding lectins indicated that epithelial GalNAc residues were present throughout the cycle. Variation in steroidally dependent 1,2 fucosyl transferase activity may therefore be responsible for the appearance of the new, DBA-binding, nonreducing terminal structure GalNAcα1,3(Fucα1,2)-Galβ1,4GlcNAcβ1 in the human during the mid-secretory phase and in the baboon during the late proliferative phase.