Endocrine and paracrine-autocrine regulation of the human corpus luteum during the mid-luteal phase

Human corpora lutea undergo an extremely rapid period of growth, developmen t and regression during the course of non-fertile cycles. The tissue consis ts of steroidogenic (parenchymal) and non-steroidogenic (stromal) cells. In women and other primates, steroid hormone production by corpora lutea depe nds on the presence of pituitary-derived LH. Nevertheless, there is also in tra-luteal regulation of steroid synthesis. Steroidogenic luteal cells and non-steroidogenic cells interact via endocrine and paracrine pathways, and by contact-dependent pathways (gap junctions). Thus, hormones and locally p roduced factors including steroids, growth factors, cytokines, reactive oxy gen species and nitric oxide may modulate luteal lifespan. The factors regu lating regression and rescue of the corpus luteum are not understood comple tely. This review describes the expression of two representative intragonad al peptides that may influence luteal regression (interleukin 1 beta) and l uteal rescue (steroidogenic acute regulatory protein).