Figure 1

Schematic representation of the functional reprogramming of regressing corpora lutea. Support for this model comes from studies in rats, in which the corpus luteum (CL) can be rescued or "reprogrammed" while already regressing by the action of androstenedione or progesterone. Which factors/hormones/drugs can function as rescuers of regressing corpora lutea in other mammalian species, needs to be investigated.