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

K. P. McNatty, D. A. Heath, N. Hudson, I. J. Clarke

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Abstract

Long-term (i.e. ~70 days) hypophysectomy led to a significant (P < 0.05) reduction in ovarian weight but no reduction in the total number of antral follicles (> 0.1 mm in diameter). In hypophysectomized ++ Booroola ewes (N = 8) follicles were always ≤ 3 mm and in hypophysectomized FF Booroola ewes (N = 6) follicles were always ≤ 2 mm in diameter; in ewes of both genotypes follicles reached diameters which were ~40% of their predicted final size at ovultion. Un in-vitro conditions, follicles from the FF and ++ hypophysectomized ewes produced significant increases in cAMP within 1 h of exposure to gonadotrophins (P < 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.

Original languageEnglish
Pages (from-to)515-522
Number of pages8
JournalJournal of Reproduction and Fertility
Volume90
Issue number2
DOIs
Publication statusPublished - 1 Jan 1990
Externally publishedYes

Keywords

  • Booroola ewes
  • cAMP output
  • F gene
  • Gonadotrophins
  • Hypophysectomy
  • Ovarian follicles

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