Chromatin Configurations and Meiotic Competence of Oocytes are Related to Follicular Diameter in Nonstimulated Rhesus Monkeys1

Abstract

Specific aims of this study were to compare relationships between size of intact antral follicles and meiotic competence, diameters, and chromatin configurations of germinal vesicle (GV) oocytes in non-gonadotropin-stimulated rhesus monkeys. Intact antral follicles were dissected from excised ovaries of nine normally cycling monkeys in the follicular phase of the menstrual cycle and of two acyclic monkeys. Follicles were classified according to diameter: I (200-450 microns), II (451-700 microns), III (701-1000 microns) and IV (> 1000 microns). Cumulus-enclosed oocytes were released from follicles and either measured (diameter) and fixed immediately or cultured for 48 h in modified CMRL medium containing 0.5 micrograms/ml ovine FSH, 10 micrograms/ml ovine LH, and 10% bovine calf serum. Following Hoechst staining, three distinct patterns of chromatin organization (GV1-3) were identified in GV oocytes according to the degree of association with the nucleolar periphery (encapsulation or "rimming"). In antral follicles > 450 microns in diameter, perinucleolar encapsulation (GV3) of oocytes before culture and meiotic maturation (metaphase II) of oocytes after culture increased (p < 0.01) with antral follicle growth in a graded fashion. While 56.3% of oocytes from large (> 1000 microns) follicles completed maturation, few (9.3%) oocytes from small (200-450 microns) follicles were competent to mature in vitro. At 0 h of culture, class IV follicles contained a greater (p < 0.01) proportion of GV3 oocytes and a smaller (p < 0.01) proportion of GV1 oocytes than classes I, II, and III follicles.(ABSTRACT TRUNCATED AT 250 WORDS)

The Effect of Ovarian Status and Follicular Diameter on Maturational Ability of Domestic Cat Oocytes

“…The relationship between follicular growth and acquirement of maturational competence of oocytes differed among species [26]. Meiotic competence of oocytes was shown concomitantly with antrum formation in adult mice [24], hamsters [7] and marmoset monkeys [24], while it was not strictly correlated with antrum formation but increased with follicular growth in cows [1], sheep [13], pigs [14,15], horses [4], humans [27] and rhesus monkeys [23]. Otoi et al [17] reported no significant relationship between oocyte diameter (range 83.5 to 126.4 µm) and maturation rate in cat ovaries stored at 38°C for 2 hr.…”

Mammalian oocyte growth and development in vitro

“…The remaining follicular somatic cells, meanwhile, undergo remarkable changes that, after ovulation, result in the formation of the carpus luteum. These events usually occur in a highly coordinated manner, although there are some notable excep-nuclear maturation; the progression of meiosis becomes arrested at metaphase I rather than metaphase I1 (De Smedt et al, 1994;Motlik et al, 1984;Schramm et al, 1993;Sorensen and Wassarman, 1976;Wickramasinghe et al, 1991). Nevertheless, these oocytes can undergo fertilization and develop to blastocysts .…”

Comparative Evaluation of Nuclear Morphology of Equine Oocytes Aspirated in vivo and Stained with Hoechst and Orcein

“…Fluorescence microscopy of oocytes stained with the DNA-specific label Hoechst has repeatedly been described for different mammalian species [Mattson and Albertini, 1990;Viuff et al, 1991;Debey et al, 1993;Hinrichs et al, 1993aHinrichs et al, , b, 1995Schramm et al, 1993;Bézard et al, 1997;Goudet et al, 1998]. For visualization of the chromatin after Hoechst staining, oocytes are usually placed between slide and cover slide, which allows precise focusing on the DNA structures Goudet et al, 1998].…”