Lactate concentrations in pre-ovulatory follicles of pro-oestrous rats before and after onset of oocyte maturation.

Lactate concentrations were determined in pre-ovulatory follicles of rats at pro-oestrus before and after onset of oocyte maturation. It appeared that high concentrations prevail before and after the time of the expected LH surge (27 mM). The level in serum was about 5 mM. Explanted oocytes obtained from pre-puberal rats and surrounded by cumulus cells, matured in the presence of 20 mM lactate as sole exogenous energy source. It is argued that oxygen may be the limiting factor suppressing oocyte maturation in vivo.