EXPRESSION OF THE CD15 DIFFERENTIATION ANTIGEN IN THE REPRODUCTIVE-TRACT OF THE FEMALE RAT DURING FETAL AND EARLY POSTNATAL ONTOGENY

The expression of the (alpha 1-->3)-fucosyl-N-acetyl-lactosamine (CD15 ) epitope in the genital tract of the female rat during fetal and earl y postnatal ontogeny was investigated by means of immunohistochemistry . CD15 was exclusively associated with epithelial cells and was mainly located along the cell membrane. The CD15 expression was characterize d, firstly, by considerable differences within the various structures and even substructures of the genital tract and secondly, by the high degree of time-related changes which accompanied the morphological dev elopment. In the Mullerian duct, CD15 was present from embryonic day ( E) 14 until birth on the apical membranes throughout the epithelial ce ll layer. In the Wolffian duct, CD15 expression was present between E1 6 and E19. Along the longitudinal extent of the Wolffian duct, express ion intensity differed, showing moderate to high levels in the epithel ial cells of the cranial and caudal parts, but without recognizable CD 15 expression in the intermediate part. In the urogenital sinus, CD15 was expressed from E15 until E21. In the cranial parts, all epithelial cells were positive, whereas in the caudal parts, CD15 was present on ly on their apical membranes. In the ovarian tube, uterine horn, and v agina, a moderate to high CD15 expression at birth gradually diminishe d to very low levels during postnatal days (P) 8 and 9. After P9, re-e xpression of CD15 occurred in the caudal part of the ovarian tube and in the uterus, increasing to a maximum at about P32. The findings prov ide (indirect) evidence for a correlation between the intensity of CD1 5 immunoreactivity and the serum concentrations of estrogens as well a s of estrogen receptors in the urogenital tract. Since steroid hormone dependency can be regarded as a gauge of the differentiation of malig nancies, it would be worthwhile correlating CD15 levels with those par ameters.