Intraovarian influence of bovine corpus luteum on oocyte morphometry and developmental competence, embryo production and cryotolerance

Three experiments were conducted to determine influence of the bovine corpus luteum (CL) on morphometric and functional characteristics of oocytes, and subsequent embryonic development. Cumulus-oocyte complexes were aspirated from two types of cows: 1) with a CL in one ovary (CL+) and without a CL in the contralateral ovary (CL-), 2) and from cows without CL in either ovary (C). Intracellular activity of the enzyme glucose-6-phosphate dehydrogenase (G6PDH), oocyte diameter and thickness of the zona pellucida were determined (Experiment 1). Then, the rate of in vitro oocyte maturation for each ovarian category was evaluated and oocyte diameter and zona pellucida thickness were measured after maturation (Experiment 2). In Experiment 3, in vitro embryo production and cryotolerance were assessed. The oocyte diameter was greater (P 0.05) or C (P = 0.0131) ovaries. Activity of G6PDH was lower in oocytes from CL+ than CL- (P