EVALUATION OF CATTLE OVARIES AND FOLLICLES BY HISTOLOGICAL ANALYSIS FOR POTENTIAL IN VITRO PRODUCTION OF EMBRYOS IN TROPICAL CONDITIONS

Abstract

Background. Reproduction is important in animal production, and follicle evaluation is a remarkable reproductive aspect by which ovaries can be accurately evaluated since ovarian follicles are the organ's functional units and each contain an oocyte and related somatic cells. Objective. The objective of this study was to evaluate the abattoir cattle ovaries and follicles for potential in vitro production of embryos. Methodology. Ovaries were collected and categorized based on the presence of corpus luteum (CL; with or without). Thereafter, ovaries were processed and follicles were counted through naked eye estimation as well histologically. Data were analyzed using the GLM procedure in SAS. Also, relationships between follicles in both types of ovaries were calculated using Pearson correlations. Results. From a total of sixteen cattle ovaries, 62.5% had absence of CL whereas 37.5% ovaries had CL. Regarding morphometric measurements, ovaries with CL were 48% higher (P < 0.05) in weight than those ovaries without CL. Correlations between length and weight in ovaries without CL were high (r= 0.87) and, diameter and weight in ovaries with CL were low (r= 0.41). Results exposed that the amount of follicles with 2-6 mm diameter were significantly (P < 0.05) higher (61% more) in ovaries without CL compared to those with CL. Primary and secondary follicles presence were higher (P < 0.05) in ovaries without CL (120% more) than in those with CL (89%). Greater (P < 0.05) numbers of normal and lower (P < 0.05) amount of degenerated follicles were found in ovaries without CL. Implications. Overall, our data suggest that ovaries without CL are a potential source for quality follicles and this study provides new insights that may serve as the baseline information to produce high-quality oocyte with potential use for in vitro production of tropical cattle. Conclusions. This study corroborated that CL influences growth and development of the follicles and cell degeneration. As a result, the developmental competence of oocytes and embryo production will be negatively affected by the ovaries with CL. Ovaries without CL will provide quality follicles and cumulus-oocyte complexes.