Relationship between the antral follicle count in bovine ovaries from a local abattoir and steroidogenesis of granulosa cells cultured as oocyte-cumulus-granulosa complexes

Abstract

The antral follicle count (AFC) is used as an indicator of cow fertility. We herein investigated the relationship between AFC and the steroidogenesis of granulosa cells and confirmed the developmental competence of oocytes derived from early antral follicles (0.5-1.0 mm) using in vitro growth culture. Slaughterhouse-derived ovaries were divided into high (≥ 25) and low (< 25) AFC groups based on AFC (≥ 2.0 mm). Oocyte-cumulus-granulosa complexes (OCGCs) collected from early antral follicles were cultured for 12 days. The total number, viability, and diameter of granulosa cells and estradiol-17β and progesterone production during the culture were evaluated. Surviving oocytes on day 12 were subjected to in vitro maturation, and their volume and nuclear status were evaluated. Some oocytes were subjected to the evaluation of developmental competence to blastocysts. Although the total number and viability of granulosa cells did not differ between the groups, granulosa cell diameters were larger in the high AFC group than in the low AFC group. The estradiol-17β and progesterone ratio on day 8 was higher in the high AFC group than in the low AFC group. Oocyte volumes and nuclear maturation rates were greater in the high AFC group than in the low AFC group. The development rate to blastocysts was 9.1% in the high AFC group, while no oocytes developed to blastocysts in the low AFC group. Therefore, estradiol-17β production by granulosa cells appears to be greater in high AFC cattle than in low AFC cattle, thereby promoting the acquisition of oocyte competence.

Antioxidative Potential of Red Deer Embryos Depends on Reproductive Stage of Hind as a Oocyte Donor

“…The antral follicle count (AFC) is used commonly as an indicator of cow fertility and according to Ireland et al and the number of follicles positively correlated with the development rate of blastocysts [38,39]. These data are in agreement with our results because the nearest number of follicles and oocytes we received from pregnant hinds, as donor of oocytes, and further the development rate in this experimental group was the lowermost.…”

Antioxidant Nobiletin Enhances Oocyte Maturation and Subsequent Embryo Development and Quality

“…Cumulus cells play an important role during oocyte growth and maturation, among them supply nutrients [ 14 ] and to mediate the effects of hormones during oocyte maturation [ 15 ]. Mingoti et al [ 16 ] demonstrated that CCs of bovine COCs can secrete E 2 and P 4 in maturation media, and Endo et al [ 17 ] and Sakaguchi et al [ 18 ], demonstrated that exogenous and endogenous E 2 by granulosa cells directly supports the in vitro development of bovine COCs. In the present study, supplementation with 25 and 50 μM nobiletin in maturation medium increase in E 2 and P 4 production by CCs.…”

Acquisition of developmental competence and <i>in vitro</i> growth culture of bovine oocytes

“…We have also tried to develop the in vitro growth (IVG) culture system for bovine small-sized oocytes (approximately 95 µm in diameter), which have no developmental competence without IVG [36,37,38,39,40,41,42,43,44,45]. In these studies, we attempted the pre-IVM culture of oocytes using IBMX after 12- or 14-day IVG culture [36, 37].…”

“…Our ultimate objectives are to establish the model of in vivo follicular development and to produce the oocytes with high developmental competence the same as in vivo matured (ovulated) oocytes; however, cultured oocyte-granulosa-cumulus complexes produce a large amount of progesterone during IVG like as degenerating follicles [41,42,43]. It means that the IVG system can be used as the model of degenerating follicles but not healthily developing follicles.…”