Formation of mammalian oocytes and their growth, differentiation and maturation within ovarian follicles

The limited knowledge on the regulation of oocyte formation, the different steps of folliculogenesis and the required conditions for oocytes to undergo proper growth, differentiation and maturation are major causes of the failure in obtaining viable offspring from in vitro cultured early oocytes from domestic animals and humans. This review highlights the factors that at present are known to be involved in the formation of mammalian oocytes and their growth, differentiation and maturation within ovarian follicles.