Menstrual Cycle and Ovulation

Understanding the physiology of follicular development is important in order to extrapolate the preclinical data to the clinical side. In this context, there has been an increasing effort to figure out the autocrine/paracrine signalling and microenvironment that will determine the fate of a follicle. The processes of atresia or further development to later stages reaching to a dominant follicle appear to be regulated by highly complicated system that consists oocyte and granulosa cell derived factors, peptides, cytokines, and sex steroids. Additionally, recent research on the menstrual cycle that yields the presence of more than one wave of follicular cohort growing within a single period will undoubtedly implicate our perception on reproductive function, hormonal contraception, and ovarian stimulation during an assisted reproduction treatment. This chapter reviews the current knowledge that reflects the timetable of a follicle throughout the early ages to the formation of dominant follicle and corresponding endometrial changes.