K. Vendola et al., Androgens promote oocyte insulin-like growth factor I expression and initiation of follicle development in the primate ovary, BIOL REPROD, 61(2), 1999, pp. 353-357
In the study reported here, we investigated the effect of androgens on recr
uitment of resting, primordial follicles into the actively growing pool. He
althy, random-cycling female rhesus monkeys were treated with testosterone,
dihydrotestosterone (DHT), or vehicle for 3-10 days, after which ovaries w
ere collected for histological analysis. The first stage of follicle growth
is the formation of the primary follicle, consisting of an oocyte surround
ed by a single layer of cuboidal granulosa cells. The number of primary fol
licles was significantly increased over time in testosterone-treated animal
s. In situ hybridization showed that androgen treatment resulted in an incr
ease to 3-fold in insulin-like growth factor I (IGF-I) and to 5-fold in IGF
-I receptor mRNA in primordial follicle oocytes. DHT effects were comparabl
e to those of testosterone, showing that these are androgen receptor-mediat
ed phenomena. These data show that androgens promote initiation of primordi
al follicle growth and implicate oocyte-derived IGF-I in this activation pr
ocess.