Testosterone synthesis by chicken follicular cells.

The roles of theca and of granulosa cells in the synthesis of testosterone (T) in ovarian follicle of hens have been studied. Theca cells alone synthesized no progesterone (P), and no or only negligible amounts of T. Granulosa cells, in contrast, without stimulation produced large amounts of P and small amounts of T. When incubated with ovine gonadotrophins, theca cells showed greater response than granulosa cells in synthesizing more T (2- to 2.5-fold increase). Combination of the two follicular cell types decreased synthesis of P, but increased that of T (9- to 17-fold). When 0.1 microgram of ovine luteinizing hormone (oLH) was added to the combined cells, T concentrations increased most dramatically, a 83-fold increase was seen after 12 h of incubation. Theca cells incubated with exogenous P also produced large amounts of T. These results indicated that in hens, theca cells may be the major site of follicular T synthesis, however, theca cells alone cannot synthesize T unless granulosa cells or P were added. It is suggested that granulosa cells may use P as a precursor, and that P is converted to T in the theca cells.