The in vitro culture supplements and selected aspects of canine oocytes maturation.

The maturation of oocytes is one of the most important steps determining their developmental competence. Due to the low percentage of oocytes of bitches that reach the MII stage, searching for reagents that may stimulate the growth and maturation of oocytes is still present in this species of mammals. The most important media supplements include gonadotropins (LH, FSH, hCG), growth factors (IGF, TGF, EGF, FGF), progesterone and follicular fluid. It is suggested that the supplement of EGF, and/or follicular cells may have an important influence on the percentage of cells that reach the MII stage. Despite plenty of research based on the improvement of bitch oocytes in vitro culture, the results obtained are still unsatisfactory. Moreover, in the long stages of canine oocytes maturation many molecular and morphological modifications (including changes in mitochondria structure and configuration in the cytoplasm) are involved. In this article, the influence of selected media supplements on the efficiency of bitch oocytes in vitro maturation was described. The molecular and morphological modifications during canine oocytes maturation were also considered in the text.