Progesterone concentration in the marsupial Sminthopsis macroura: relationship with the conceptus, uterine glandular regeneration and body weight

Abstract

Close examination of hormonal profiles and uterine morphology in the marsupial reproductive cycle highlights significant differences between pregnant and non-pregnant cycles. In the polyovular dasyurid marsupial Sminthopsis macroura, we identified changes associated with gestation by comparing ovarian and plasma progesterone concentrations, uterine weights, uterine epithelial mitoses, body weights and gestation lengths between pregnant and non-pregnant luteal phases. The plasma progesterone profile of S. macroura was biphasic, peaking during unilaminar blastocyst expansion and on the day of implantation. Periods of rapid embryonic development were associated with increasing plasma progestero..