Page "False pregnancy" Paragraph 11

The corpus luteum ( the remains of an ovulated ovarian follicle ) is responsible for the development of maternal behavior and lactation, which are mediated by the continued production of progesterone by the corpus luteum through some or all of pregnancy.

In most species the corpus luteum is degraded in the absence of a pregnancy.

However, in some species, the corpus luteum may persist in the absence of pregnancy and cause " pseudopregnancy ", in which the female will exhibit clinical signs of pregnancy.