Morphocytometric Assessment of Oocytes Recoverd from Superovulated Autochthonous Breeds of Sheep

Abstract

The aim of this paper was to assess the mophocytometric examination of oocytes recovered from superovulated autochthonous breeds of sheep (Transylvanian Merino, ligaie, lurcana). The research has been carried out during August – November 2010 (breeding season) on 30 sheep, aged between 1,3 and 6 years. The assessment of superovulatory treatment response involved median laparatomy technique. In order to put into practice the IVM/IVF protocols, the selection of ovine oocytes was based on morphologic exam, but most important, on mophometric measurements. After three hormonal treatments, were visualized 197 follicles in Transylvanian Merino, 130 follicles in ligaie sheep and 84 follicles in lurcana sheep. Applying the method of follicular aspiration the best results were obtained from Merino sheep (158 oocytes) followed by ligaie sheep (97 oocytes) and lurcana sheep (55 oocytes). Based on the morphological characters identified (appearance of the zona pellucida, cumulus ooforus, cytoplasm, perivitelin space) sheep oocytes collected were classified into two quality categories: „cultivable” oocytes (Merino - 83.69%, ligaie - 81.44%, lurcana -78.18%) and „non-cultivable” oocytes (Merino - 16.31%, ligaie - 18.36%, lurcana -21.82%). Morphocytometric analysis was performed with the Images Plus Motic microscope software, studing the zona pellucida and cumulus thickness and diameter oocyte. Morphocytometric measurements made, allowed us a new reclassification of oocytes into four quality classes: class I, class II, class III, class IV. The results suggest that is necessary to complete morphological examination with morphocytometric measurements through further structural information they provide.