Zona pellucida metric evaluation related to cell viability of bovine oocytes

Abstract

The objective of this work was to establish a protocol for the metric evaluation of the zona pellucida and apply the metric values in relation to oocyte viability. Thirty-two oocytes collected from the slaughterhouse and classified into atresic and non-atresic were evaluated. Non-atresic oocytes were firstly morphologically evaluated and then metrically evaluated, through which it was possible to measure the corona radiata, zona pellucida and diameter of the antrum in mm. From the results obtained, it was possible to calculate the mean of the measured values. The corona radiata of the 10 oocytes showed mild degeneration with mean values of 27.10 mm, the zona pellucida was intact with a mean of 2.45 mm and the antrum diameter, which maintained almost constant values, had a mean of 58.75 mm. As for the morphology-mean ratio of the corona radiata, it can be observed that oocytes with lower morphological degrees (I and II) had, on average, a greater mean size of the corona radiata compared to oocytes with higher degrees (III and IV). There was no relationship between the morphology of the oocyte and the zona pellucida. As for the antrum diameter, it can be observed that the only grade IV oocyte had the smallest antrum diameter among the analyzed oocytes. Metric analysis can establish good quality cell parameters and facilitate choice for procedures.