title: Ovarian characteristics in sheep with multiple fecundity genes.
abstract: Ewes heterozygous for combinations of the Inverdale (FecXI; I+), Booroola (FecB; B+) and Woodlands (FecX2W; W+) mutations have ovulation rates higher than each mutation separately. The aims of the experiments described herein were to examine the ovarian phenotypes in I+B+ and I+B+W+ ewes and to compare these with the appropriate ++ (controls), I+ and BB animals available for this study. The mean ± s.e.m. ovulation rates in the ++ (n = 23), I+ (10), I+B+ (7), I+B+W+ (10) and BB (3) animals were 1.8 ± 0.1, 2.5 ± 0.2, 6.6 ± 1.0, 9.6 ± 0.9 and 9.7 ± 0.9 respectively. The maximum number of granulosa cells per follicle in the ++ and I+ genotypes was accumulated after exceeding 5 mm diameter, whereas in I+B+, I+B+W+ and BB animals, this was achieved when follicles reached >2-3 mm. The number of putative preovulatory follicles, as assessed from those with LH-responsive granulosa cells, 24 h after the induction of luteolysis, was higher (P < 0.01) in the I+B+ and I+B+W+ compared to the ++ and I+ genotypes. The median follicular diameters of these follicles in the ++, I+, I+B+, I+B+W+ and BB genotypes were 6, 5, 3, 3 and 3 mm respectively. The total number of granulosa cells in the putative preovulatory follicles when added together, and total mass of luteal tissue, did not differ between the genotypes. Thus, despite large ovulation rate differences between animals with one or more fecundity genes, the total cell compositions over all preovulatory follicles and corpora lutea, when added together, are similar to that from the one or two such follicles in the wild types.
authors.affiliation: Victoria University of WellingtonWellington, New Zealand Kenneth.mcnatty@vuw.ac.nz.
authors.forename: Kenneth P
authors.initials: KP
authors.lastname: McNatty
authors.affiliation: Victoria University of WellingtonWellington, New Zealand.
authors.forename: Derek A
authors.initials: DA
authors.lastname: Heath
authors.affiliation: Victoria University of WellingtonWellington, New Zealand.
authors.forename: Zaramasina
authors.initials: Z
authors.lastname: Clark
authors.affiliation: University of OtagoDunedin, New Zealand.
authors.forename: Karen
authors.initials: K
authors.lastname: Reader
authors.affiliation: AgResearchInvermay Agricultural Centre, Mosgiel, New Zealand.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Juengel
authors.affiliation: Victoria University of WellingtonWellington, New Zealand.
authors.forename: Janet L
authors.initials: JL
authors.lastname: Pitman
mesh_terms: D000818:Animals; D002452:Cell Count; D003338:Corpus Luteum / Q000033:anatomy & histology; D005260:Female; D005298:Fertility / Q000235:genetics*; D005640:Follicle Stimulating Hormone / Q000494:pharmacology; D005838:Genotype; D006107:Granulosa Cells / Q000166:cytology / Q000187:drug effects; D007986:Luteinizing Hormone / Q000494:pharmacology; D009154:Mutation; D009929:Organ Size; D006080:Ovarian Follicle / Q000166:cytology; D010053:Ovary / Q000502:physiology*; D010060:Ovulation / Q000235:genetics; D010641:Phenotype; D011247:Pregnancy; D034561:Sheep, Domestic / Q000235:genetics*
chemical_list: D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone