Cortical granule complements in human oocytes undergoing partial zona dissection

This study was performed to evaluate the effects of mechanical stimulation and sucrose treatment on the oocyte activation process. Fresh and aged human oocytes were exposed to sucrose and zonae were dissected with microneedles before fixation and quantitative analysis of cortical granules by transmission electron microscopy. Examination of the mean number of cortical granules/analyzed segment revealed no significant differences between control oocytes or oocytes treated with sucrose or sucrose treatment followed by zona dissection. A significant decline in the number of cortical granules/segment was observed for oocytes undergoing prolonged culture after dissection (P less than 0.05). Thus, zona dissection and sucrose exposure of freshly aspirated mature human oocytes do not result in classical oocyte activation.