**1. Introduction**

Many peptides are responsible for the coordination of functions in reproductive tissues, including angiotensin II (ANG II). In the oviduct, ANG II induces morphological and physiological alterations in the infundibulum, ampulla, and isthmus to provide an ideal microenvironment for oocyte transport and maturation, sperm capacitation and transport, and fertilization and early embryonic development.

In the ovary, the AT2 receptor is important for ovulation in many species (cattle, rats, and rabbits) and follicle stimulating hormone (FSH) is an important regulator in bovine granulosa

cells *in vivo* and *in vitro*. Moreover, the presence of this system in bovine, caprine and procine fetal ovaries ovaries suggests a role in preantral follicle development. In addition, in female germ cells, ANG II plays a key role in the oocytes during in vitro maturation in porcine and Cattle. In male reproduction as an important role in spermatogenesis to guarantee fertilization.

Aiming to clarify the localization, role, and practical implications of the renin-angiotensin system (RAS) in male and female reproductive biology, this chapter highlights the roles of RAS in mammalian reproductive physiology, specifically, in the ovaries, testes, oviducts, and other reproductive tissues.
