FSH Actions on Sertoli Cell Secretions in Stationary and Superfused Cultures

It is commonly accepted that FSH is essential for the initiation of spermatogenesis in the sexually maturing rat (1) and that Sertoli cells (Sc) are the primary site of FSH action in the testis (2, 3). The testicular development during puberty is accompanied by dramatic changes in Sc responsiveness to FSH (4, 5), the formation of the blood-testis barrier (6), and the appearance of first postmeiotic germ cells in the seminiferous epithelium (7). There is increasing evidence suggesting that all of these events are interrelated, but the precise role of FSH during the maturational process is still not very clear. The functional and morphological complexity of the testis make it difficult to study FSH actions in vivo. Thus, much of our knowledge on the regulation of Sc functions has been derived from experiments conducted in vitro with Sc cultures. Two culture techniques have been employed recently for this purpose: the superfusion culture system (8) and the two-compartment culture system (9). The superfusion system is particularly well suited for defining the kinetics of Sc secretions and their responses to FSH, whereas the two-compartment system can be used to investigate the regulation of Sc vectorial secretions and the development of the blood-testis barrier. Our results concerning FSH actions on Sc secretions and the formation of Sc tight junctions are summarized below.