Fig. 4.

Major molecular mechanisms and regulatory elements involved in the control of luteolysis in the cycling ovary. LH secreted by the pituitary gland and CG secreted by the uterus during the early pregnancy period ensure maintenance of CL  and continuous synthesis of progesterone. Signaling pathways controlled by LHCGR-PKA regulatory axis suppress apoptosis and autophagy until the levels of LH and CG decrease (left side of the figure). If the pregnancy did not occur or is at late stages, then the uterus produces PGF2α, which initiates luteolysis through the promotion of extrinsic apoptosis and destructive autophagy (right side of the figure). The induction of apoptosis through death receptors is dependent on the presence of immune cells which express FasL. Orange circles with the letter “P” indicate protein phosphorylation, red crosses indicate the lack or suppression of certain regulators, and dashed elements indicate the regulators and connections that are not definitively confirmed up to date