Perspectives on the corpus luteum of the menstrual cycle and early pregnancy

Recent advances support the concept of vital luteotropic roles for pituitary (LH) and placental (CG) gonadotropins during the menstrual cycle and early pregnancy, respectively. However, the precise roles and mechanisms whereby the gonadotropic hormones influence the primate corpus luteum are not well understood. The physiologic luteolysin(s) and/or processes limiting the functional lifespan of the corpus luteum in the menstrual cycle remain a mystery. Research is focusing on steroidal and nonsteroidal products of the ovary, or the corpus luteum itself, which may have important paracrine actions regulating luteal function. Cell biologists are finally examining the hypothesis proposed by histologists in the early 1900s that the corpus luteum consists of a heterogeneous population of luteal cells. By elucidating the origin(s), products, endocrine/paracrine regulatory mechanisms, and cellular dynamics of luteal cells, we may better understand the events that produce the normal activity and lifespan of the corpus luteum during the menstrual cycle and early pregnancy. Likewise, we may begin to define and modify the sequelae leading to luteal dysfunction and impaired fertility in select types of reproductive disorders.