Changes in the Distribution of Cell Surface Glycoconjugates of Mouse Sertoli Cells during Fetal Testicular Development

Changes in the lectin binding of differentiating mouse fetal testes were examined by light and electron microscopy, with close attention paid to those in the cell surface glycoconjugates of fetal Sertoli cells during the formation of testicular cords. In undifferentiated testes on day 12 post coitum (p.c.), ConA, RCA-I and WGA showed similar binding patterns; that is, the internal gonadal somatic tissue was weakly positive. After the formation of testicular cords (on day 13 p.c.), differentiated Sertoli cells came to be positive for these three lectins. Thereafter, reactivity with ConA and WGA increased, while that with RCA-I disappeared by day 16 p.c. Moreover, electron microscopic observations revealed changes in the WGA binding on the plasma membranes of somatic cells. That is, before testicular cord formation, WGA binding was restricted to the plasma membranes of some testicular somatic cells (pre-Sertoli cells) facing neighboring germ cells. After formation of the testicular cords, the WGA was bound to the plasma membranes between Sertoli cells, showing that WGA binding existed all along the plasma membranes of Sertoli cells. These findings suggest that the cell surface glycoconjugates on Sertoli cells may play an important role in the formation of testicular cords packed with both germ cells and Sertoli cells.