title: Ovarian activity in Booroola X Romney ewes which have a major gene influencing their ovulation rate.
abstract: A marked difference in both the function and composition of individual ovarian follicles was noted in Booroola X Romney ewes (6-7 years of age) which had previously been segregated on at least one ovulation rate record of 3-4 (F + ewes, N = 21) or less than 3 (++ ewes, N = 21). Follicles in F + ewes produced oestradiol and reached maturity at a smaller diameter than in ++ ewes. In F+ ewes (N = 3), the presumptive preovulatory follicles were 4.4 +/- 0.5 (s.e.m.) mm in diameter and contained 2.1 +/- 0.3 X 10(6) (s.e.m.) granulosa cells, whereas in ++ ewes (N = 3), such follicles were 7.3 +/- 0.3 mm in diameter and contained 6.5 +/- 0.8 X 10(6) cells. During a prostaglandin (PG)-induced follicular phase, the secretion rate of oestradiol from ovaries containing 3 presumptive preovulatory follicles in F + ewes was similar to that from ovaries with only one such follicle in ++ ewes. We suggest that the putative 'gene effect' in F + ewes is manifested during early follicular development and that it may be mediated via an enhanced sensitivity of granulosa cells to pituitary hormones. As a consequence, the development of 3 preovulatory follicles in F + ewes may be necessary to provide a cell mass capable of producing the same quantity of oestradiol as that from one preovulatory follicle in ++ ewes.
mesh_terms: D000735:Androstenedione / Q000378:metabolism; D000818:Animals; D001141:Aromatase / Q000378:metabolism; D001947:Breeding; D004958:Estradiol / Q000378:metabolism; D005260:Female; D005496:Follicular Atresia; D005838:Genotype; D007986:Luteinizing Hormone / Q000494:pharmacology; D006080:Ovarian Follicle / Q000378:metabolism / Q000502:physiology*; D010060:Ovulation; D011374:Progesterone / Q000378:metabolism; D012756:Sheep / Q000235:genetics*; D013739:Testosterone / Q000378:metabolism; D013799:Theca Cells / Q000187:drug effects
chemical_list: D013739:Testosterone; D000735:Androstenedione; D011374:Progesterone; D004958:Estradiol; D007986:Luteinizing Hormone; D001141:Aromatase