134 Estradiol improves cattle oocyte maturation rate in vitro
M. D. Sebopela A B , M. L. Mphaphathi B C , S. M. Sithole A B and T. L. Nedambale A BA Tshwane University of Technology, Department of Animal Science, Pretoria, Republic of South Africa
B Agricultural Research Council, Animal Production, Germplasm, Conservation, Reproductive and Biotechnologies, Irene, Republic of South Africa
C University of the Free State, Department of Animal, Wildlife and Grassland Sciences, Bloemfontein, Republic of South Africa
Reproduction, Fertility and Development 34(2) 305-305 https://doi.org/10.1071/RDv34n2Ab134
Published: 7 December 2021
© 2022 The Author(s) (or their employer(s)). Published by CSIRO Publishing on behalf of the IETS
Oestrogen is used to improve the nuclear and cytoplasmic maturation of oocytes in vitro as well as the expansion of the cumulus cells; however, the role of oestradiol remains controversial. This is because a high concentration of oestradiol inhibits spindle formation and polar body extrusion in cattle oocytes. The aim of the study was to examine the effects of various levels (0, 0.1, 0.2, 0.3, 0.4, and 0.5 µg mL−1) of oestradiol ontheIVM rate in cattle oocytes. Cattle ovaries from matured cows were collected from a local abattoir and transported to the laboratory in a thermo flask at 37°C. Oocytes were recovered from ovaries using the aspiration method. Collected oocytes were washed in modified Dulbecco’s PBS and modified M199 and then matured in 500 µL of TCM 199 medium supplemented with 10% fetal bovine serum, FSH, LH, and different concentrations of oestradiol before being covered with 250 µL of mineral oil. The oocyte maturation rate was determined by expansion of cumulus-oocytes complexes (COCs) and extrusion of the polar body after 22 h of IVM. Each treatment was matured with 200 oocytes and replicated 10 times. Data was analysed using the GenStat® statistical program (VSN International). Comparisons were considered not significantly different (P > 0.05) using Fisher’s protected least significant difference test. Supplementation of IVM medium with oestradiol at concentrations of 0 (88 ± 3.77), 0.1 (90.0 ± 1.41), 0.2 (89.90 ± 3.44), 0.3 (90.30 ± 3.40), 0.4 (89.30 ± 3.16), and 0.5 µg mL−1 (87 ± 3.47) resulted in no significant difference in COC expansion, respectively (P > 0.05). Polar body extrusion at 0 (2.42 ± 4.39), 0.1 (21.00 ± 7.194), 0.2 (46.70 ± 14.68), 0.3 (47.30 ± 11.05), 0.4 (29.90 ± 8.19), and 0.5 µg mL−1 (23.40 ± 9.85) oestradiol was recorded (P < 0.05). In conclusion, oestradiol improves the maturation rate in cattle oocytes at concentrations of 0.2 and 0.3 µg mL−1. Further studies are required to improve cattle oocyte meiotic competencies in vitro.
