Proliferative activity of oocytes in multi-oocyte follicles of bovine ovary

We characterized the proliferative activity of multi-oocyte follicles with anti-nuclear antigen of proliferating cells (PCNA). Ovaries (n = 12) from heifers were processed for histology. From 789 multi-oocytes follicles observed, only 11 were considered appropriated for immunostaining, since they presented all nuclei of the oocytes clearly visible. All multi-oocyte follicles were positive for PCNA, but some oocytes showed no proliferative activity. We conclude that oocytes in multi-oocyte follicles seem to be in different stages of the cell cycle.