Estudo morfológico de complexo Cumulus oophorus ovinos obtidos de folículos antrais em diferentes fases do ciclo estral da gestação

Abstract

It was carried out a morphological study on Oocyte Cumulus Complex of sheep (COCs), in order to characterize them quantitatively, both during the proestrus and diameter phases of the estrous cycle, as during different periods of the gestation. COCs were collected from antral follicles (3-6 mm) with regular, slightly grainy and multiple layers of cumulus cytoplasm (COC Grade I) fixed on glutaraldehyde and embedded in paraffin, as well as sectioned into sections of 5 μm. The principle of the nucleator was used to estimate average volumes of oocytes, cumulus cells and their nuclei. The thicknesses of the pellucida zone, as well as the numerical percentages of different types of cumulus cells were evaluated. There was a synchronous increase of the volume of the oocyte and its nucleus from diestrus to proestrus phases. Concerning the ones collected in the gestation stages, there was a parameter volume reduction as the pregnancy progresses. The thickness of the pellucida zone was reduced during the periods approaching ovulation. Three types of cumulus cells were observed (C1-C3). The results suggest that cumulus cells respond to circulating hormone levels during the estrous cycle and gestation.