DISTINCT CHANGES IN THE LAMININ COMPOSITION OF BASEMENT-MEMBRANES IN HUMAN SEMINIFEROUS TUBULES DURING DEVELOPMENT AND DEGENERATION

We studied the distribution of laminin (Ln) chains and their integrin (Int) receptors in normal developing and adult and in atrophied human testes by using immunohistochemistry. Immunostaining for EHS Ln and ty pe IV collagen was used to identify basement membranes (BMs). In the B M of seminiferous epithelium of fetal testis, a panel of monoclonal an tibodies showed immunoreactivity for Ln alpha 1-, alpha 2-, beta 1-, b eta 2- and gamma 1-chains, suggestive of the presence of Lns 1 to 3. I n BM of adult seminiferous epithelium with active spermatogenesis, imm unoreactivity for Ln beta 2- and gamma 1-chains was found but not for Ln alpha-chains, suggesting a complex of Ln chains not compatible with any known trimers. Instead, with polyclonal In antiserum and monoclon al antibody to type IV collagen, a distinct BM-like reactivity was see n. In atrophied testes, prominent immunoreactivities for Ln chains, co mpatible with Ins I to 3, were seen in the thickened BM of seminiferou s tubules, hence suggesting of reappearance of fetal Lns. Among the su bunits of Ln-binding Int receptors in fetal seminiferous tubules, a st rong immunoreactivity for Int beta(1)- and Int alpha 6-subunits was se en throughout the seminiferous epithelium, other Int subunits being fo und in interstitial cells, In the adult and atrophied testes, immunore activities for Int beta(1)- and Int alpha(6)-subunits were seen to be confined to the basal aspect of the seminiferous epithelium whereas im munoreactivities for Int alpha(1)-, alpha(2)-, alpha(3)(-) and beta(4) -subunits were seen in the myoid cells. The results show that both mat uration and degenerative changes of human testes are accompanied by di stinct changes in the In expression of BM of seminiferous epithelium, which appears to accompany epithelial differentiation of the Sertoli c ells. Furthermore, they suggest the presence of a novel Ln trimer in B M of adult human seminiferous tubules.