Cellular components involved in luteolysis.

In the domestic species, regression of the corpus luteum is dependent on uterine release of prostaglandin (PG)F2 alpha. Despite the central role of PGF2 alpha in luteolysis, very little is known about the actual mechanism of prostaglandin-induced regression at the level of the luteal cell. Many studies have focused on the cellular site of action of PGF2 alpha, and it seems likely that this compound exerts multiple effects on luteal cells. Large luteal cells probably respond initially to the luteolytic signal, but intercellular communication between large and small cells, as well as between luteal and non-luteal cells, is probably required for regression to proceed. The immune system seems to be actively involved in the process of luteolysis, and it is possible that luteal cells actively signal certain types of immune cells. It is now known that luteal cells respond to a variety of immune cell secretory products, and this knowledge may lead to the discovery of additional mechanisms involved in regression of the corpus luteum.