Efeito do estresse térmico na maturação in vitro de oócitos caprinos e ovinos em protocolos de produção de embriões

Abstract

This study aimed to determine the Effect of heat stress during maturation of oocytes and in vitro production of embryos in goats and sheep. Ovaries were collected in a slaughterhouse and transported to the Laboratory of Biotechnical Reproduction of UFRPE. The cumulus oophorus complexes (COCs) were collected by the technique of "slicing" of the follicles from 2 to 6 mm in diameter and selected based on morphological classification and placed on the basic stages. In 10 replicates the COCs were submitted to the caloric heat stress at 41 ° C for 0 (the thermoneutral 39° C), 3, 6, 12, 18 and 24 hours of maturation in vitro. The percentage of oocytes was determined in the maturation, fertilization, cleaved (D-3), stage of 8-16 cells (D-4), morale (D-5), blastocyst(D-8) after fertilization and blastocyst positive for apoptosis by TUNEL assay. Significant difference (P < 0.05) in all time periods of heat stress in ripening. In sheeps the fertilization, D-3,D-4, D-5 and D-8 was not significantly different (P > 0.05) between the times of 18 vs 24 hours in blastocyst TUNEL positive at 0 vs 3, 3 vs 6, 12 vs 18 and 18 vs 24 h of heat stress. The results in goats showed on maturation, fertilization, D-3, D-4, D-5. The D-8 was not significantly different (P > 0.05) between the periods of 3 vs 6 to 18 vs 24 h and the blastocyst TUNEL positive at 0 vs 3, 3 vs 6, 12 vs 18 and 18 vs 24 h of heat stress. Under the conditions observed in this study, the results indicate that the time in which the oocyte is exposed to heat stress during maturation in vitro is essential to define the embryonic development and their level of apoptotic cells.