Histochemical study of lectin binding to gestational endometrium.

Avidin-biotin-peroxidase labeling technique was used to localize the binding sites of concanavalin A, peanut agglutinin, and Ulex europaeus in 30 formalin-fixed paraffin-embedded samples of gestational endometrium in intrauterine and ectopic pregnancy, in comparison with 23 samples of normal endometrium at different stages of the menstrual cycle. Concanavalin A shows strong affinity to decidual cells; in normal endometrium its affinity to stroma is weak to moderate. Ulex europaeus, which is weakly positive in normal endometrium, demonstrates focal strong reaction with epithelium and intraluminal secretions in some of the gestational glands. Peanut agglutinin is the most remarkable marker of pregnancy-related changes in endometrium, being strongly positive in the apical portions and intraluminal secretions of the glands; in nonpregnant endometrium its binding capacity is weak.