The role of steroidogenic and nonsteroidogenic luteal cell interactions in regulating progesterone production.

The corpus luteum is an extremely important reproductive endocrine gland that influences numerous physiological processes and is therefore perhaps the most widely studied reproductive endocrine structure to date. The corpus luteum and its major product, progesterone, are central to any discussion of impaired reproductive performance. It is generally agreed that our best chances for reducing reproductive losses lie in a thorough understanding of the mechanisms controlling luteal function during reproductive cycles and pregnancy. Normal corpus luteum function is dependent on numerous regulatory factors, such as prostaglandins, oxytocin, steroids, growth factors, cytokines, etc. Recently, increased interest in studying luteal cell interactions (steroidogenic large and small luteal cells as well as nonsteroidogenic "accessory" cells of the corpus luteum) has produced new evidence of communication within the corpus luteum that influences its function. The exact means of communication among the luteal cells are not known; however, this interaction seems to involve both luteotropic and luteolytic actions and can occur through either contact-dependent and contact-independent mechanisms.