Morphological and biochemical characteristics during ovarian follicular development in the pig

Publisher Website
Google Scholar
Abstract
Ovaries were recovered from groups of naturally cyclic pigs (N= 5) on each of Days 16, 18, 20 and 21 of the oestrous cycle. Follicular diameter, follicular fluid volume and concentrations of oestradiol, testosterone and progesterone, and granulosa cell number were determined in all follicles .ltoreq. 2 mm in a diameter (n=511). In alternative follicles either granulosa cell aromatase activity and theca testosterone content or 125I-labelled hCG binding to granulosa and theca were determined. The mean total number of follicles recovered per animal decreased as the follicular phase progressed and a strong positive relationship (P < 0.001) existed between follicular diameter and volume on all days. The number of granulosa cells recovered per follicle was variable, and not related to oestrogenic acitivity of the follicles. Mean follicular fluid oestradiol, testosterone and 125I-labelled hCB binding all increased until Day 20 and decreased on Day 21, whereas mean theca testosterone content, 125I-labelled hCG binding to theca tissue and aromatase were all maximal on Day 21. On Days 20 and 21 a subset of 14-16 larges follicles was readily distinguishable from the remaining smaller, less oestrogenically active population in each animal. Yet, consistently within these subsets there was a difference in follicular diameter of .apprx. 2.0 and also a considerable range of biochemical development even among follicles of equal size. These results indicate asynchrony at the time of recruitment and selection among follicles destined to ovulate and suggest that heterogeneity continues into the immediate preovulatory period.

This publication has 19 references indexed in Scilit: