Implementación de un protocolo de maduración in vitro de ovocitos de cobaya (Cavia porcellus)

Abstract

One of the strategies used worldwide for the multiplication and conservation of material of high genetic value or in danger of extinction is the production of in vitro embryos. The objective was to evaluate an in vitro maturation protocol for cumulus-oocyte complexes (COC´s) from guinea pigs (Cavia porcellus). 760 COC´s corresponding to 52 ovaries were obtained using the Slicing technique. The COCs were selected according to the methodology described by Hawk and Wall (1994) and modified by Ayala et al. (2019) for bovine COC´s (type A; B; C). Once the COC´s of each type were obtained, 20% was used for pre-maturation morphometry, another 20% was used as a control and went directly to the in vitro maturation process (IVM) for 24 h. The remaining 60% was applied the Brilliant Cresyl Blue (BCB) test and growth (BCB+) and those that were still growing (BCB-) were determined, then each type and its subgroups (BCB+ and BCB-) were matured. in vitro for 24 hours. Finally, the percentage of maturation and post-maturation morphometry were established. The recovered oocytes were morphologically classified as 35.8% type A COC´s, 30.9% B and 33.3% type C. It was determined that 71.6%, 60%, 63.5% of COC´s type A, B and C respectively reacted to the BCB test. When performing the morphometry, it was established that the COC´s of Type A and B (suitable) were larger than the unsuitable COC´s (type C), with a statistical difference. The COC´s of the control group of type A, matured in 40.4%, types B 31.7% and type C 18.2%. However, the percentage of nuclear maturation was affected when COC´s of types A; B and C, were subjected to the BCB test and subsequently matured for 24 hours. In conclusion: the maturation medium used allowed the oocytes to reach metaphase II; however, these percentages are much lower than expected.