MECHANISMS ASSOCIATED WITH CORPUS-LUTEUM DEVELOPMENT

The transition of a preovulatory follicle into a corpus luteum is a co mplex process involving mechanisms similar to wound healing and tumor formation. The objective of this review is to focus on mechanisms asso ciated with corpus luteum development with specific attention to the f ollicular lineage of luteal cells, mechanisms associated with luteiniz ation, and neovascular changes during luteal development. Corpora lute a are a continuation of follicular maturation and form from granulosal and theca interna cells. There is morphological and immunological evi dence in ruminant species for the differentiation of granulosal and th eca interna cells into large and small steroidogenic luteal cells, res pectively. Different morphological, physiological, and morphological, endocrinological, and biochemical changes associated with luteinizatio n. Luteinization involves the transition of a preovulatory follicle in to a highly vascular corpus luteum capable of secreting large quantiti es of progesterone. In addition, various cell types undergo hyperplasi a, hypertrophy, and(or) migration during corpus luteum formation. An e ssential component of corpus luteum development is the recruitment of a blood supply. The development of a new microcirculatory bed involves breakdown of the follicular basement membrane, endothelial cell migra tion, endothelial cell proliferation, and development of capillary lum ina. This process is regulated by the interaction of angiogenic and an tiangiogenic substances. Further clarification of the preceding mechan isms may result in the development of improved methodologies for contr olling the time of ovulation and(or) increasing pregnancy rates.