Effect of long-term hypophysectomy on ovarian follicle populations and gonadotrophin-induced adenosine cyclic 3',5'-monophosphate output by follicles from Booroola ewes with or without the F gene.
Long-term (i.e. approximately 70 days) hypophysectomy led to a significant (P less than 0.05) reduction in ovarian weight but no reduction in the total number of antral follicles (greater than 0.1 mm in diameter). In hypophysectomized ++ Booroola ewes (N = 8) follicles were always less than or equal to 3 mm and in hypophysectomized FF Booroola ewes (N = 6) follicles were always less than or equal to 2 mm in diameter; in ewes of both genotypes follicles reached diameters which were approximately 40% of their predicted final size at ovulation. Under in-vitro conditions, follicles from the FF and ++ hypophysectomized ewes produced significant increases in cAMP within 1 h of exposure to gonadotrophins (P less than 0.05) although no genotypic differences in cAMP production were noted. We conclude that ovarian follicles in FF and ++ ewes have absolute requirements for pituitary hormone on reaching diameters of 2 mm and 3 mm respectively and that appreciable numbers of antral follicles in ewes of both genotypes remain responsive to pituitary gonadotrophins despite prolonged deprivation of these hormones.
McNatty
K P
KP
MAFTech, Wallaceville Animal Research Centre, Upper Hutt, New Zealand.
Heath
D A
DA
Hudson
N
N
Clarke
I J
IJ
D000818:Animals; D000242:Cyclic AMP / Q000096:biosynthesis*; D005260:Female; D005640:Follicle Stimulating Hormone / Q000494:pharmacology; D005796:Genes; D006065:Gonadotropins, Pituitary / Q000494:pharmacology*; D007016:Hypophysectomy; D007986:Luteinizing Hormone / Q000494:pharmacology; D009929:Organ Size; D006080:Ovarian Follicle / Q000033:anatomy & histology / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D010053:Ovary / Q000033:anatomy & histology; D010902:Pituitary Gland / Q000502:physiology*; D012756:Sheep / Q000235:genetics* / Q000502:physiology*; D013997:Time Factors
D006065:Gonadotropins, Pituitary; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D000242:Cyclic AMP