Andrade Amorim, ChristianiCharif, DaniaDaniaCharif2025-05-142025-05-142025-05-142024https://hdl.handle.net/2078.2/36689From puberty onwards, folliculogenesis occurs in the ovaries and enables the cyclic release of a mature oocyte. This highly regulated process begins with a primordial follicle that undergoes various stages of maturation before reaching the final stage of development, known as the Graafian follicle. During the secondary stage, an important event occurs: the appearance of an additional layer of cells. This newly obtained layer, known as the theca layer, contains an important cell type called the theca interna cells (TICs). These cells display steroidogenic activity enabling them to synthesize female steroid hormones required for the ongoing growth and development of the follicle. Although TICs were discovered many years ago, their origin is still unknown. Understanding the origin of these cells could improve our comprehension of the physiology of the female reproductive system. In addition, these cells could be used to develop the transplantable engineered ovary (TEO) as well as a suitable model for studying ovarian diseases such as polycystic ovary syndrome (PCOS) and premature ovarian insufficiency (POI). According to literature, the adult ovarian stroma is believed to accommodate theca stem cells (TSCs) that share specific characteristics with mesenchymal stem cells (MSCs). Our study aims to investigate the existence of ovarian-specific MSCs within the ovarian stroma, which may correspond to the previously described TSCs. To explore this hypothesis, TICs were differentiated from postmenopausal ovarian stromal cells and subsequently characterized throughout their differentiation process. In addition, we investigated the ability of human adipose-derived stem cells (ADSCs) to differentiate into TICs under the same conditions as ovarian stromal cells. The experimental results obtained so far indicate that TICs may be derived from ovarian stromal cells, with cells exhibiting specific markers for TICs already after two days in culture. Similarly, initial findings suggest that MSCs may be present during the in vitro differentiation and have the ability to differentiate into TICs under these specific culture conditions. In conclusion, the insights gained from this study will contribute to the better understanding of theca cells’ origin, suggesting a possible origin from MSCs.theca cellsmesenchymal stem cellsovarian follicle developmentfertility preservationsteroidogenesisdifferentiationtext::thesis::master thesisthesis:44237