Plasma concentrations of progesterone and 13,14-dihydro-15-keto-prostaglandin F-2 alpha during regression of the corpora lutea of lactation in the bandicoot (Isoodon macrourus).

Plasma progesterone concentrations (mean +/- s.e.m.) declined from 7.5 +/- 1.2 ng/ml and 7.5 +/- 1.0 ng/ml to less than 1 ng/ml after removal of pouch young (RPY) from bandicoots at Days 24 and 30 of lactation respectively. In all 7 bandicoots, the corpora lutea of lactation showed signs of regression and, in 5 of these bandicoots, a premature ovulation had occurred 6-9 days after RPY. There was no change in the concentration of PGFM after RPY, and uterine prostaglandin F-2 alpha may not be involved in luteal regression in the bandicoot.