Ontogeny of ovarian follicle development in Booroola sheep fetuses that are homozygous carriers or non-carriers of the FecB gene

摘要

The aims of this study were to examine the effects of the Booroola FecB gene on ovarian development and reproductive hormones (FSH, LH and inhibin) at days 90, 100, 120 and 135 of gestation (term = 147 days). The effects of litter size were eliminated by transferring equal numbers of homozygous BB and control (++) embryos to recipient ewes. The ovary, but not the body, pituitary, adrenal, kidney or thymus, was heavier (P ++), in the number of primordial follicles at days 100 (BB > ++) and 135 (BB > ++), and also in the number of primary or secondary follicles (++ > BB) at day 135. At each gestational age examined no differences were noted with respect to the plasma concentrations of FSH, LH or inhibin between the BB and ++ fetuses. However, the highest mean plasma concentrations of FSH and LH occurred at days 90 and 100 of gestation, which coincided with the first developing primary follicles. Collectively, the results from this and previous studies show that the different effects of the FecB gene in germ cell development in early gestation continue throughout fetal development independently of litter size. Moreover, during the growth of the first primary and secondary follicles at days 100 and 120, respectively, there are no differences in the plasma concentrations of FSH, LH and inhibin with respect to Booroola genotype.