Corpus luteum development and angiogenesis

Abstract

Development of the corpus luteum (CL) is vital for the early increase in postovulatory progesterone that drives embryo development and the successful establishment of pregnancy. Following ovulation, rapid and dramatic cellular reorganisation and intense angiogenesis are required to support the timely transition to progesterone secretion. In addition to inherent physiological challenges, this process is sensitive to any imbalance in metabolism or health, particularly in the modern high yielding dairy cow. This makes luteal inadequacy a common cause of poor early embryo development and low conception rates in dairy cows. This review will explore the potential mechanisms that underlie this disorder. It will describe the impact that the pre-ovulatory follicle infrastructure, gonadotrophin support and size of the LH surge have on subsequent luteal development and function. A crucial component for rapid luteal growth is the formation of new blood vessels or angiogenesis. Several recent studies have highlighted the critical importance of fibroblast growth factor 2 (FGF2) in regulating this process. In particular, FGF2 has a profound influence on endothelial cell sprouting and branching. There is increasing evidence that pericytes, immune cells and platelets are also integral regulators of luteal angiogenesis and development. The complex and dynamic nature of luteal development means that it is likely to be sensitive to potential inadequacies particularly, in the high producing dairy cow.