Ultrastructural studies of glycan changes in the apical surface of the uterine epithelium during pre-ovulatory and pre-implantation stages in the marmoset monkey

It has been postulated that carbohydrates are involved in a variety of cell -cell interactions including blastocyst implantation. In primates, there ar e only limited investigations on the ultrastructural localisation of the cy clic changes in uterine epithelial surface carbohydrates. Our aim was to in vestigate such changes during the pre-ovulatory and pre-implantation stages of the reproductive cycle in the marmoset monkey. After fixation of endometrial tissues, avidin-ferritin lectin cytochemistry was employed for apical surface glycan detection at the ultrastructural le vel. Five lectins were used including Canavalia ensiformis (Con A), Lotus t etragonolobus (LTA), Glycine max (SBA), Phytolacca americana (PWM) and Trit icum vulgaris (WGA). Morphometry was used to quantitate changes in the inte nsity of lectin staining by determining the total number of ferritin partic les per unit length of membrane. Surface and intra-cytoplasmic vesicles, st ained by the lectins, were also examined. Quantitative ferritin assessment showed that 1 day before presumed implanta tion (days 11 to 12 after ovulation in the marmoset monkey) there was a sig nificant increase in Con A, LTA and SEA staining on the apical uterine epit helial plasma membrane compared to the pre-ovulatory phase and earlier stag es of pregnancy (days 4-8 after ovulation). A significant increase in PWM w as also detected from early pregnancy to preimplantation stages. All lectin s except WGA produced reproducible staining within reproductive cycle group s. The greatest variation and intensity of epithelial surface staining was observed with WGA and the weakest with LTA. The patchy staining with LTA co mpared with thick coverage by WGA indicated the complexity of the carbohydr ate arrangement in the glycocalyx of the uterine surface plasma membrane. R eduction of WGA reactivity after neuraminidase treatment suggested that the lectin binding might be related to the presence of heavily sialylated apic al uterine membrane glycoconjugates. This is the first high-resolution study in primates to report quantitative cyclic changes in fucosyl, galactosyl, glucosyl, and mannosyl sugar residue s of the apical uterine epithelial glycocalyx. The findings support the con cept that uterine epithelial glycocalyx surface carbohydrates play a role i n preparing a receptive uterine surface. Anat Rec 255:241-251, 1999. (C) 19 99 Wiley-Liss, Inc.