Concentrations of oestradiol-17β in plasma and corpora lutea throughout pregnancy in the tammar, Macropus eugenii

Abstract

Oestradiol-17β concentrations were measured by radioimmunoassay in peripheral blood samples from 10 tammar wallabies after their pouch young were removed to terminate embryonic diapause. Oestradiol concentrations rose from 8.3 ± 1.2 pg/ml on Days 3 and 4 to a peak of 15.8 ± 2.9 pg/ml on Day 5, coincident with an increase in 'progesterone' concentrations, and then fell to 10.5 ± 2.7 pg/ml on Day 7. No changes in oestradiol concentrations were associated with parturition. Five females came into oestrus and mated 9.8 ± 6.1 h post partum; peak concentrations of plasma oestradiol (20.9 ± 2.1 pg/ml) occurred around the time of mating. None of the females that did not mate up to the end of the expe..