*2.3.6 Prostaglandin F2<sup>α</sup>*

In the absence of pregnancy, the average life span of the CL is controlled by the release of endometrial PGF2α source, establishing a bimodal pattern of discharge around day 13–16 of diestrus. While the first 4-h peak precedes the decline of P4, the second occurs during and after luteolysis. Luteolysis involves decreased blood supply, leukocyte infiltration, cell disruption and loss of lutein steroidogenic capacity by apoptotic or non-apoptotic mechanisms intended to disintegrate the CL and therefore secretion P4 [39, 40].
