Estrogens and progesterone during gestation in Dolichotis patagona.

During pregnancy, a progesterone-binding plasma protein is present and is similar in several respects to the binding protein reported in other hystricomorphs. These findings establish estradiol-17 beta as the predominant estrogen of pregnancy and that progesterone rises during pregnancy and does not decline until after parturition. Gestation length is 96 days. This study establishes similarities between the mara and its closest relative, the guinea pig.