Relationship of Macroscopic Appearance of the Surface of Bovine Ovarian Follicles, Concentrations of Steroids in Follicular Fluid, and Maturation of Oocytes in Vitro1

Abstract

The relationship among opaqueness of the surface of bovine ovarian follicles, concentrations of follicular steroids, and capacity of oocytes to achieve nuclear maturation in vitro was examined in this study. Follicles greater than or equal to 5 mm in diameter were classified as clear (n=68) or opaque (n=72) based on their surface appearance. An oocyte and follicular fluid (FF) were removed from each follicle. Each oocyte was cultured, and the concentration of estradiol (E), progesterone (P), and testosterone (T) was determined for each sample of FF. Oocytes that extruded the first polar body by 30 h in culture were considered mature. All other oocytes were immature. More (p less than 0.05) mature oocytes came from clear (56%) than opaque follicles (29%). Clear follicles had lower concentrations of E (p less than 0.05) and P (p less than 0.10) in FF than opaque follicles. Follicles with mature oocytes had greater (p less than 0.05) concentrations of P than follicles with immature oocytes. Follicles were separated into three categories based on ratio of P:E in FF: high = P:E greater than or equal to 10, medium = P:E greater than or equal to 1 less than 10, and low = P:E less than 1. The percentage of mature oocytes from clear follicles was similar for high (64%), medium (48%), and low (57%) P:E groups; however, the percentage of mature oocytes from opaque follicles was greater (p less than 0.05) for the high (59%) than for the medium (21%) or low (19%) P:E groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Measurement of redox potential and steroid concentrations in the follicular fluid of growing and regressing follicles of mares

“…The results reported here are in accordance with those of previous studies showing different oestradiol concentration of atretic and intact follicles in cattle and horses (Grimes and Ireland, 1986;Guilbault et al, 1993;Goudet et al, 1999;Ginther et al, 2002), although they did not indicate differences between nonatretic and early atretic follicles. In contrast to some previous studies, the highest progesterone concentrations were found in follicles with the quickest increase of diameter (McNatty et al, 1984;Grimes and Ireland, 1986;Guilbault et al, 1993). However, in conformity with the findings of these authors the progesterone concentrations of the follicular fluid were higher in regressing follicles than in small growing follicles.…”

Increasing Exogenous Progesterone during Synchronization of Estrus Decreases Endogenous 17β-Estradiol and Increases Conception in Cows1

“…However, structural changes associated with oocyte maturation are associated with changes in steroid concentrations. Concentrations of P 4 and E 2 that develop in the preovulatory follicle may be involved in oocyte maturation in cattle [23]. Elevated intrafollicular concentrations of E 2 were postulated to prevent premature nuclear maturation of bovine oocytes in vivo [23].…”

“…Concentrations of P 4 and E 2 that develop in the preovulatory follicle may be involved in oocyte maturation in cattle [23]. Elevated intrafollicular concentrations of E 2 were postulated to prevent premature nuclear maturation of bovine oocytes in vivo [23]. When oocytes were examined within a few hours of removal from a follicle, less than 10% of bovine oocytes had completed meiosis I or II [24][25][26].…”

Pregnancy Rate is Greater When the Corpus Luteum is Present during the Period of Progestin Treatment to Synchronize Time of Estrus in Cows and Heifers1

“…Intrafollicular estrogen is thought to be involved in modulation of the maturation process of bovine oocytes [15]. Exposure of oocytes to abnormally high concentrations of estrogen over extended periods of time could lead to abnormal development of oocytes in bovine females treated with norgestomet.…”