Plasma progesterone through pregnancy and the estrous cycle in the eastern quoll, Dasyurus viverrinus

Plasma progesterone concentrations were measured every 2 or 3 days in eastern quoll, Dasyurus viverrinus, during pregnancy (20.5 +/- 0.8 days, n = 6, mean +/- SEM) and the estrous cycle (37.5 +/- 0.7 days, n = 20, mean +/- SEM). The pattern was not apparently different between the two reproductive states. There was a significant proestrus rise in progesterone (from 0.5 to 4 ng/ml) from 5 days before until 1 day after mating. For the next 4 to 6 days, levels were low, but after Day 9 or 10 increased to maximum concentrations of 4.5 to 15 ng/ml which were maintained until about Day 17 to 19. In all females, progesterone was basal (less than 1.0 ng/ml) by Day 20 to 21 and thereafter remained low in lactating females, but nonpregnant females showed a proestrous rise about 5 to 7 days before the next mating. The period of elevated concentrations of progesterone coincided with prominent corpora lutea (CL) on the ovaries. There was no evidence of CL of a previous cycle persisting into the next cycle. The results indicate that pregnancy occupies the luteal phase of the cycle and does not appear to influence the secretory life span of the CL.