Ultra-structural study of Egyptian Buffalo oocytes before and after in vitro maturation

Abstract

The purpose of this study was to describe the changes occurring in the cytoplasmic organelles of the buffalo oocytes before and after in vitro maturation. The total number of oocytes used in this experiment was 250 oocytes; 50 in vivo matured oocytes, 100 immature oocytes, and the other 100 was in vitro matured oocytes cultured in TCM-199 + LH. The oocytes examined in this study showed normal ultra-structure of mitochondria, smooth endoplasmic reticulum (SER), zona pellucida (ZP), lipid droplets, vesicles and Golgi in the good type meanwhile, some differences and abnormalities in denuded oocytes were recorded. The most remarkable changes observed in the two different categories of oocytes (good and denuded) after maturation was the different complexes consisting endoplasmic reticulum, mitochondria (M), lipid droplets (L), vesicles (V) and ZP. Concerning the polar body (PB), group of in vitro matured oocytes showed a normal PB formation, vesicles, whereas mitochondria were dislocated towards the site of the PB. In vitro matured oocytes showed clusters of cortical granules which existed in aggregates throughout the peripheral ooplasm just beneath the oolemma. In vitro maturation of Egyptian buffalo oocytes could be elucidated by alterations that occurred in the cytoplasmic organelles of the oocytes as shown by transmission electron microscopy (TEM).

Keywords: Egyptian buffalo, oocytes, in vitro maturation, ultra-structure