Growth factors as autocrine and paracrine modulators of male gonadal functions

Departments of Anatomy and Cell Biology, Obstetrics and Gynecology, and Urology, and the Center for Reproductive Sciences, College of Physicians and Surgeons, Columbia University, 650 West 168th Street, New York, NY 10032, USA Keywords: growth factors; testis Introduction Growth and differentiation of the male gonads involves a complex sequence of interactions between soma and germ cell elements. These interactions are mediated principally by the trophic hormones, FSH, LH, GH and prolactin, and the sensitive autocrine and paracrine actions of growth factors. During fetal and neonatal life, development of the gonads requires the differential expansion of epithelial and mesenchymal tissues to form the interstitial and epithelial compartments, respectively, of the testes (Bellvé & Feig, 1984). In pubertal and adult animals, the onset and maintenance of spermatogenesis require an exact temporal regulation of germ cell proliferation and differentiation. For both events there must be an array of local growth factors