Insights into in vivo follicle formation: a review of in vitro systems

Abstract

In vitro systems capable of reconstituting the process of mouse oogenesis are now being established to help develop further understanding of the mechanisms underlying oocyte/follicle development and differentiation. These systems could also help increase the production of useful livestock or genetically modified animals, and aid in identifying the causes of infertility in humans. Recently, we revealed, using an in vitro system for recapitulating oogenesis, that the activation of the estrogen signaling pathway induces abnormal follicle formation, that blocking estrogen-induced expression of anti-Müllerian hormone is crucial for normal follicle formation, and that the production of α-fetoprotein in fetal liver tissue is involved in normal in vivo follicle formation. In mouse fetuses, follicle formation is not carried out by factors within the ovaries but is instead orchestrated by distal endocrine factors. This review outlines findings from genetics, endocrinology, and in vitro studies regarding the factors that can affect the formation of primordial follicles in mammals.

NTS, NTSR1 and ERs in the Pituitary–Gonadal Axis of Cycling and Postnatal Female Rats after BPA Treatment

“…It has been shown in some mammalian species that the absence of estrogens in early embryonic life affects normal ovarian development, as they are fundamental in the process of germ cell proliferation and the initiation of primordial follicle formation [ 68 ]. Therefore, disturbed estrogen exposure can have permanent adverse consequences, such as tumor formation [ 72 , 73 ]. The onset of sensitivity to endogenous or exogenous estrogens is clearly related to the ontogeny of ERα and/or ERβ expression, which varies in different organs, tissues, and cells.…”

In focus in HCB: new histochemical insights into mammalian gametogenesis

“…Although the molecular mechanisms underlying follicular development are still unclear, factors (e.g., genes, signaling molecules, and targets) that control the different stages of folliculogenesis continue to be identified. Tanimoto et al (2021) review genetics, endocrinology, and in vitro investigations of factors that can affect follicle formation in mammals. A current in vitro system is capable of achieving the entire process of oogenesis for recapitulating oogenesis.…”