The fine structure of the luteal cells in relation to the concentration of progesterone in the plasma of the lactating bandicoot, Isoodon macrourus (Marsupialia: Peramelidae)

The ultrastructure of the corpora lutea of lactation in the bandicoot I. macrourus has been correlated with the concentration of progesterone in the maternal plasma. The circulating level of progesterone declined from a maximum of 12-3 ± 1-6 (SE) ng ml-1(n=ll) early in lactation at days 0-10 post partum, to 4-1 ± 0-4 (SE) ng ml-1 (n = 25) at days 11-57. This change in hormone concentration is in accord with the loss of densely staining granules from the luteal cells