Morphological and functional characterization of large antral follicles in three breeds of XXXX with different ovulation rates.

@entity251 @entity742 @entity2931 @entity53 @entity1146
Morphological and functional features of large ovarian follicles from three breeds of @entity742 , with different ovulation rates (Finnish Landrace N = 12, Finnish Landrace X Scottish Blackface N = 16, Merino X Scottish Blackface N = 16) were compared by integrating three techniques; ink labelling, in-vitro @entity53 production and morphological classification. The follicles were removed at two stages of the follicular phase, 1 (PG + 1) or 2 (PG + 2) days after PGF-2 alpha treatment and compared after monitoring their rates of growth with the use of ink labelling. After ovariectomy all follicles greater than or equal to 1 mm in diameter were dissected, and the 8 largest were incubated individually for 2 h to assess their ability to secrete @entity53 and @entity251 . After incubation the follicles were processed for histological examination and checked for @entity1146 . An analysis of the follicle population was based on in-vitro @entity53 secretion rates in all three breeds; an @entity2931 -active population producing 500-8100 pg @entity53 /ml/h and an @entity2931 -inactive population producing 0-499 pg @entity53 /ml/h. A comparison of the 3 approaches demonstrated agreement on 94.3 +/- 1.2% of occasions. Ink-labelling demonstrated that all follicles identified as @entity2931 -active were increasing in size. Within @entity2931 -active follicles significant correlations were detected between @entity53 production and @entity251 production (r = 0.42), @entity53 production and granulosa cell number (r = 0.45) and between @entity53 production and mitotic index (r = -0.38). A regression model fitting breed, stage of @entity1146 , granulosa cell number, in-vitro @entity251 production and mitotic index demonstrated that granulosa cell number is a characteristic which contributes significantly to the variation of in-vitro @entity53 production in @entity2931 -active and @entity2931 -inactive follicles. There was no significant difference between breeds in the mean number of ink-labelled follicles growing from Day PG - 1 to Day PG + 1. There was a significant difference between the breeds in the number of ink-labelled follicles growing between Days PG + 1 and PG + 2 (Days 1 and 2 of the follicular phase), the number being similar to the ovulation rate for the breed. The majority of the @entity2931 -active follicles had been recruited by Day PG - 1, although in the Finnish Landrace genotypes more than 30% were recruited on or after Day PG + 1 compared to less than 10% in Merino x Scottish Blackface ewes.(ABSTRACT TRUNCATED AT 400 WORDS)
