EFFECTS OF THE BOOROOLA GENE (FECB(B)) ON BODYMASS, TESTIS DEVELOPMENT AND HORMONE CONCENTRATIONS DURING FETAL LIFE

In female fetuses the Booroola gene (FecB(B)) is known to affect germ cell development and consequently the pattern of ovarian follicular gr owth during fetal and post-natal life. However in males, the role of t his gene during fetal development is unknown. The aims of the study re ported here were to examine the effects of the FecB(B) gene on develop ment of male fetuses with respect to body and organ mass (for example, pituitary gland, adrenal and mesonephros), testes development, includ ing numbers of germ cells, and also the plasma concentrations or tissu e contents of the reproductive hormones (FSH, LH and testosterone) at days 40, 55, 75, 90 and 135 of gestation. The FecB(B) gene was found t o influence litter size, bodymass, crown-rump length and testis mass a t most stages of gestation. Some effects were also noted on the mesone phros at days 40 and 55 and on the pituitary and adrenal at days 90 or 135 of gestation. However, the FecB(B) gene was not observed to have an effect on the patterns of germ cell development, on pituitary conte nt or plasma concentrations of immunoreactive or bioactive FSH or immu noreactive LH or testicular content of testosterone. When embryo trans fer experiments were performed to eliminate the effects of litter size at days 40, 90 and 135 of gestation nearly all of the differences in bodymass, crown-rump length and organ mass disappeared. The only excep tion to this was at day 90 when bodymass continued to be lighter and c rown-rump lengths smaller in the BB/B + fetuses compared with the ++ f etuses; the significance of this finding remains unknown. It is conclu ded that for Booroola male fetuses there are no direct effects of the FecB(B) gene on pituitary gonadotrophin function or testicular develop ment after sexual differentiation. Moreover, although there may be tem poral differences around day 90 of gestation, there are no long-term, direct effects of the FecB(B) gene on total body, adrenal, testis or p ituitary mass. Collectively these findings for the male are similar to those for female fetuses except with regard to germ cell development.