Immunohistochemical study of galectin-3 in mature and immature bull testis and epididymis

Abstract

Galectin-3, a member of the beta-galactoside-binding protein family, has been implicated in mammalian sperm maturation. We examined galectin-3 expression in the testis and epididymis of sexually mature and immature bulls. Western blot analysis showed varying levels of galectin-3 in the bull testis and epididymis, and galectin-3 immunoreactivity was higher in the mature testis and epididymis than in immature organs. Galectin-3 was primarily localized in interstitial cells of the immature bull testis and in the peritubular myoid and interstitial cells of the mature testis. In the immature epididymis head, galectin-3 was primarily in the principal and basal cells of the epithelium. In the mature epididymis head, moderate levels of galectin-3 were detected in the sperm, while low levels were found in the stereocilia, epithelium and connective tissue. In the immature epididymis body, moderate protein levels were detected in the principal cells, while lower levels were found in the basal cells. The mature epididymis body showed moderate levels of galectin-3 immunostaining in the stereocilia and epithelium, but low levels in the connective tissue. In the immature epididymis tail, only low levels of galectin-3 staining were found in the epithelium, whereas the mature epididymis tail showed high levels of galectin-3 in the principal cells, moderate levels in the basal cells and low levels in connective tissue. These findings suggest that galectin-3 expression plays a role in the maturation and activation of sperm in bulls.

Fig. 1

Western blot analysis of galectin-3 in bull reproductive tissue. Differential expressions of galectin-3 in the immature and mature testis and epididymis. Lower panel shows the expression of the internal control, β-actin, in the same membrane. T, testis; M, mature; IM, immature; E, epididymis.

Fig. 2

Immunohistochemical staining of the immature (A, D-F) and mature (B, G-I) testis (A, B) and epididymis (D-I). C shows a negative control section in which the primary antibody was omitted. Sections were counterstained with hematoxylin. Scale bars = 50 µm.

Fig. 3

Immunofluorescent co-localization of galectin-3 with isolectin B4. (A-C) The mature head, (D-F) body and (G-I) tail of the epididymis. (A-F) Arrows show galectin-3 immunoreactivity in isolectin B4-positive macrophages. (G-I) Arrowheads indicate galectin-3 immunoreactivity in isolectin B4-positive mucosal epithelium. C, F, and I are merged images. Scale bars = 20 µm.