Influence of Stage of Cycle, Corpus Luteum Location, Follicle Size, and Number of Large Follicles on Estradiol-17β Concentrations in Bovine Follicles

Abstract

Concentrations of estradiol-17 beta in follicular fluid were correlated to follicular size, stage of estrous cycle, location of corpus luteum, and presence of large follicles. Paired ovaries were obtained from 481 nonpregnant cows at slaughter and follicles were classified as ipsilateral or contralateral to the corpus luteum. Follicular fluid estradiol-17 beta concentrations from 2494 small, 1485 medium, and 396 large follicles were quantified by radioimmunoassay. Stage of estrous cycle was estimated by visual examination of the corpus luteum. Follicles in stage 1 of the estrous cycle (d 1 to 4) had the highest estradiol-17 beta concentration and the smallest mean follicular diameter. Location of follicles relative to the corpus luteum had no influence on estradiol-17 beta concentrations. As follicular size increased, concentration of estradiol-17 beta also increased. The presence of a single large follicle did not affect the concentration of estradiol-17 beta in medium or small follicles. In contrast, if multiple large follicles occurred in the same cow, concentrations of estradiol-17 beta were significantly lower in medium but not small follicles.

Ultrasonographic Biometry of the Ovaries of Pregnant Kundhi Buffaloes

“…However, both the buffaloes had follicles in their ovaries. The same relationship between the size and number was reported in cows [19]. Ginther et al [20] reported a decrease in the dominant follicle diameter after day 90 of cow pregnancy.…”

An essential role for the intra-oocyte MAPK activity in the NSN-to-SN transition of germinal vesicle chromatin configuration in porcine oocytes

“…Thus, it was expected that most of the medium (subordinate) follicles would suffer FSH insufficiency and undergo atresia at this stage of follicle selection 37 . In both cows 38 and sows 39 , the concentration of E2 increased significantly with increasing follicular sizes. Studies in the human suggested that GDF9 levels in the follicular fluid were highly correlated with oocyte nuclear maturation and embryo quality 40 .…”

Postmortem comparison of ultrasonography, endocrine measurements and histology of large abnormal ovarian follicles in cows

“…The presence of a corpus luteum had no effect on the follicle hormone concentration within sets of ovaries. Thus, it can be accepted that corpora lutea have no direct influence on steroid concentration within follicles (Brantmeier and others 1987).…”