In ruminants, regression of the CL is due to a positive feedback loop between endometrial prostaglandin (PG) F2α (PGF2α) and luteal oxytocin secretion (Flint et al. 1992). The common factor associated with luteolysis in cattle and sheep appears to be an increase in endometrial sensitivity to oxytocin due to presence of oxytocin receptor (OTR) that may lead to initiation of luteolysis (McCracken...
