Developmental changes and sex difference in glucose-6-phosphate dehydrogenase activity of bovine oocytes and embryos fertilized in vitro.

The developmental changes and sex difference in activity of glucose-6-phosphate dehydrogenase (G-6-PDH) of bovine oocytes and early embryos derived from follicular oocytes fertilized in vitro were histochemically examined. Bovine embryos at two- to eight-cell stages were separated into two halves by pipetting after removal of zona pellucida by treating with 0.5% pronase. One half was assayed for G-6-PDH activity and the other was used to determine sex by chromosome analysis. There was no definite tendency in G-6-PDH activity from matured oocytes to the eight-cell embryos and no activity was observed at morulae stage. We found no sex difference in the G-6-PDH activity of bovine two- to eight-cell embryos derived from follicular oocytes. A high activity was observed in some embryos with four or six X-chromosomes.