A note on the inhibition of in vitro meiotic maturation of mammalian oocytes by dibutyryl cyclic AMP

Cytogenetic data are presented which indicate species differences in the response of oocytes maturing in vitro in the presence of dibutyryl cyclic AMP (dbcAMP). Inhibition of ewe oocyte maturation was noted at germinal vesicle, MI, and MII in the presence of 25–750 μg/ml of dbcAMP. Cow oocytes were primarily affected at MI and MII by similar concentrations, and only 750 μg/ml delayed golden hamster oocytes at these stages. These findings highlight the variability between the responses of the oocytes of these mammals and the rat, mouse, or pig.