Effects of gonadotropins upon the incidence and kinetics of meiotic maturation of macaque oocytes in vitro

Abstract

The specific aim of this study was to determine the effects of gonadotropins in vitro upon the incidence of and precise time interval to germinal vesicle breakdown (GVB) and extrusion of the first polar body (PB1) in oocytes from nonstimulated rhesus monkeys. Cumulus-enclod germinal vesicle (GV) stage oocytes from 10 normal, cycling rhesus monkeys in the follicular phase of the menstrual cycle were cultured with either: (1) 1.0 micrograms/ml human follicle-stimulating hormone (hFSH), (2) 10 micrograms/ml human luteinizing hormone (hLH), (3) 1.0 microgram/ml hFSH and 10 micrograms/ml hLH, or (4) no gonadotropins (controls). Oocytes (n = 234) were examined at 3-hr intervals from 0 to 21 hr and at 4-hr intervals from 24 to 52 hr for GVB and PB1. Neither the incidence of GVB (hFSH: 63.5%; hLH: 56.1%; both gonadotropins: 63.1%; no gonadotropins: 53.6%) nor extrusion of PB1 (hFSH: 41.3%; hLH: 36.4%; both gonadotropins: 36.9%; no gonadotropins; 31.9%) differed (P > 0.05) among treatments. The time to GVB was accelerated (P < 0.05) by gonadotropins (hFSH: 10.8 +/- 1.7 hr; hLH: 10.1 +/- 1.8 hr; both gonadotropins: 8.8 +/- 1.1 hr) when compared to controls (17.4 +/- 2.0 hr). However, the time interval to extrusion of PB1 did not differ (P > 0.05) among treatments (hFSH: 32.3 +/- 1.2 hr; hLH: 35.1 +/- 1.4 hr; both gonadotropins: 35.2 +/- 1.3 hr; no gonadotropins: 34.1 +/- 1.2 hr). The mean interval to extrusion of PB1 was 34.1 +/- 0.6 hr.(ABSTRACT TRUNCATED AT 250 WORDS)

Maturation, Fertilization, and Development of Marmoset Monkey Oocytes in Vitro

“…In oocytes from untreated marmosets, the competence to resume and complete meiosis and the time course of nuclear progression in vitro was highly dependent on the size of the follicle from which the oocyte originated. Marmoset oocytes from intermediatesized antral follicles exhibit a notably higher capacity to meiotically mature in vitro (90-100%, [7] and present study) than oocytes from macaques (15-56%, [10,[26][27][28]) and humans (17-68%, [12,[29][30][31][32]). In unprimed marmosets, oocytes from the smallest antral follicles have a lower meiotic potential than oocytes from larger antral follicles, and those that are able to mature do so more slowly.…”

“…The present study has shown that marmoset oocytes require appreciably less time in vitro to mature (20-24 h) than do oocytes from rhesus monkeys (30-34 h, [27,46]) and humans (36-47 h, [32,47]); this time period is more comparable to that required by oocytes of domestic ungulates (16-27 h, [45,[48][49][50][51]). Oocytes from the largest follicles (> 1.4 mm; found only in FSH-primed marmosets) presented an anomaly in the relationship between follicle size and the timing of meiotic maturation in that they tended to mature more slowly than those from smaller follicles, although this was nonsignificant because of the small numbers of oocytes in this class.…”

“…In unprimed marmosets, oocytes from the smallest antral follicles have a lower meiotic potential than oocytes from larger antral follicles, and those that are able to mature do so more slowly. The importance of follicle size in determining oocyte maturation potential has been comprehensively documented in many species (reviewed in [33,34]), including primates (present study; [6,7,10,27,28]). These studies illustrate that events occurring in the later stages of antral development modulate oocyte cytoplasmic maturation, expressed in a higher rate (speed) of meiosis, a higher capacity to complete meiosis, and enhanced developmental potential.…”

Cumulus-Oocyte Complexes from Small Antral Follicles During the Early Follicular Phase of Menstrual Cycles in Rhesus Monkeys Yield Oocytes That Reinitiate Meiosis and Fertilize In Vitro1

“…Both human and macaque oocytes isolated from large antral follicle resume spontaneous meiosis [52,[71][72][73][74]. In nonhuman primates [42,60,69,70], as in women [75,76], gonadotropin priming in vivo has been shown to increase the number of oocytes collected and improve their maturation as well as to enhance the embryonic competence. In contrast, oocytes from small follicles unresponsive to an ovulatory gonadotropin surge or from dissected ovaries collected at unknown stages of the menstrual cycle, presumably from small follicles not exposed to gonadotropins, are also used in human IVM, but their competence is lower [29,31,32,[77][78][79][80][81].…”

“…This source of the COCs is distinct from those in previous reports using both nonhuman primates and women. Most prior studies evaluating IVM in nonhuman primate models used oocytes from large antral follicles of monkeys primed with FSH for 6-7 days [42,60,69,70]. Both human and macaque oocytes isolated from large antral follicle resume spontaneous meiosis [52,[71][72][73][74].…”