EN
In this review, the main features of folliculogenesis in pigs are summarized because normal follicular development of an oocyte that is capable of fertilization and embryonic development. Folliculogenesis begins in early fetal life. Nevertheless, the precise signal for the initiation of follicular growth in pigs remains unknown. Specific feature of follicles is that porcine theca interna cells possess an active aromatase system. In addition, morphological and functional characteristics ovarian follicles of pigs shows that porcine granulosa cells are the major site of progesterone synthesis. It is generally accepted that among domestic species, pigs are the only species that do not have follicle waves during the estrous cycle. However, it has been recently demonstrated that waves of follicular development occur before puberty and during pregnancy in pigs. Follicular growth in pigs is dependent on endocrine and paracrine factors, such as gonadotropins, steroids, metabolic hormones, growth factors and other regulatory peptides. Furthermore, studies of morphologically follicles in the pig indicate that follicular development is dependent on the oocyte. The oocyte secretes factors essential for both oocyte and follicular somatic cell function and development.