Efecto del estadio del ciclo estral y de la categoría de los complejos cúmulo-ovocito (COC’s) sobre las características morfológicas y funcionales de ovocitos de cobaya (Cavia porcellus)

Abstract

The objective was to evaluate the characteristics of cumulus-oocyte complexes obtained at different stages of the estrous cycle and their relationship with the morphological and functional characteristics of guinea pig oocytes. Forty guinea pigs aged 3 to 9 months were synchronized with REGUMATE® (0.22 mg/kg) for 15 days. After 2 and 10 days after progestogen withdrawal, the ovaries were collected and COC's were obtained by serial sections and classified into type A, B and C. Forty percent of the COCs were used to determine G6PDH enzyme activity and to measure the distribution of cytoplasmic lipid droplets, while the remaining 60% were used to measure cytoplasmic diameter and volume, to study nuclear progression and the rate of apoptosis. The BCB test evidenced a higher proportion of BCB+ oocytes in the periovulatory than in the diestrous. The distribution of lipid droplets in the cytoplasm was significant in the diestrous, observing that type A and C oocytes were similar in terms of uniform lipid distribution; whereas, type B oocytes, had a slightly higher percentage with central lipid distribution. In the apoptosis rate, there was a lower percentage in the periovulatory phase than in the diestrous phase. Nuclear status showed a higher percentage of mature oocytes in the periovulatory than in the diestrous. Oocyte diameter and volume showed that oocytes were significantly larger in the diestrous than in the periovulatory.