In the bovine ovary there is a delay of 4-6 days between the observed maximum of oxytocin mRNA and the peak in the luteal levels of oxytocin nonapeptide. This implies a maturation process involving components of the post-translational processing pathway. In situ hybridization shows the oxytocin gene to be transcribed exclusively in the large cells of the corpus luteum at the beginning of the estrous cycle.