Relationship of meiotic prophase and ornithine decarboxylase in the neonatal rabbit ovary

Ornithine decarboxylase (ODC) activity was measured in homogenates of neonatal rabbit ovaries from the day of birth to day 22, an interval that corresponds to the progressing stages of the meiotic prophase from oogonia to diplotene and follicle formation. The ODCactivity was high on days 1 and 3 when most germ cells start the phase of pre-meiotic DNA-synthesis. A peak of ODC-activity appeared on day 12, simultaneously with a small increase in mitotic activity of the intraovarian rete cells. It is suggested that ODC and therefore polyamine synthesis may be related to the regulation of the onset of meiosis and the mitotic activity of the intraovarian rete cells.