Galectin-1 and galectin-3 are abundantly expressed at implantation sites in the uterus, suggesting their involvement in the establishment of pregnancy. In this study, we examined the expression and localization of galectin-1 and galectin-3 in fallopian tubes from nonpregnant women, and in those presenting with tubal ectopic pregnancy. There was no significant difference in the expression of either galectin-1 (LGALS1) or galectin-3 (LGALS3) transcripts in the fallopian tube across the menstrual cycle. Their expressions in the fallopian tube were inversely correlated to each other (r = -0.5134, p < 0.0001) and differentially localized. Galectin-1 protein was abundant in the stroma of nonpregnant fallopian tubes, whereas galectin-3 was mainly localized to the epithelium, notably to the cilia of ciliated cells and the apical cytoplasm of secretory cells. In ectopic pregnancies, LGALS3 expression was significantly reduced (p < 0.0001), but LGALS1 expression did not change when compared to nonpregnant fallopian tubes collected during the mid-secretory phase. The percentage of fallopian tube epithelial cells expressing galectin-3 in cilia tended to be reduced (p = 0.0685), with an accompanying loss of a normal ciliary structure, while nuclear galectin-3 increased (p < 0.05) in ectopic pregnancies. Epithelial immunostaining for galectin-1 tended to be elevated in fallopian tubes from women with ectopic pregnancy. Coculture of human trophoblast origin SW71 cells significantly increased LGALS1 expression in human fallopian tube epithelial OE-E6/E7 cells, suggesting that trophoblast-derived products regulate LGALS1 expression in the oviductal epithelium. These findings imply a differential contribution of galectin-1 and galectin-3 in the homeostasis of human fallopian tubes and in the pathophysiology of ectopic pregnancy. (C) 2015 S. Karger AG, Basel