© 1975 by The Society for Integrative and Comparative Biology
Studies on Spermatogenesis and Steroidogenesis in Culture
Program in Reproductive Biology and Endocrinology, The University of Texas Medical School at Houston Houston, Texas 77025
This paper summarizes the major pertinent findings of previously published work and includes new experimental data. Culture conditions have been defined for long-term maintenance of basic testicular structure, primitive type A spermatogonia, and Sertoli cells. The primitive type A spermatogonia grown for 8 weeks in organ culture were capable of restoring complete spermatogenesis after the cultures were transplanted into the testes of sexually mature homologous hosts. Since the primitive type A spermatogonia were the only germinal elements present in the organ cultures at the time of transplantation, they probably represent the spermatogenic stem cells. Differentiation of gonocytes or spermatogonia to spermatocytes in late pachytene stage required presence of vitamins A, C, and E or 4 mM concentration of glutamine in the medium but was not affected by hormones. The replication of Sertoli cells in vivo and in organ culture was shown to be age related and hormone independent. The Sertoli cells possess specific FSH binding receptors and respond to FSH with increased synthesis of c-AMP and androgen-binding protein. The biologic function of FSH in the Sertoli cells remains to be clarified. Other cellular components of the testis, the germinal, or peritubular cells do not bind FSH. In organ cultures of testicular tissue or Leydig-cell cultures all enzymes in the steroid biosynthetic pathway, leading from progesterone to testosterone, remain active for several days. In older cultures, the conversion of progesterone to testosterone becomes impaired primarily due to loss of two specific enzymes: 17
hydroxylase and 17-20 lyase. Addition of HCG to monolayer cultures of Leydig cells stimulated both the synthesis and release of testosterone.