DIRECT EFFECT OF TESTOSTERONE HORMONE ON EMBRYO GASTRULATION STAGE

Gastrulation is the short developmental window in which an embryo reorganizes into a three-layered body plan and establishes the first major axes. In humans it occurs around the third week of development and is driven by primitive streak formation, coordinated cell ingression, and signaling through pathways such as Wnt, Nodal, and BMP [5]. Because steroid hormones can reshape transcription, metabolism, and cytoskeletal behavior, testosterone has been proposed as a potential modifier of gastrulation, especially in pregnancies complicated by hyperandrogenism. However, “direct effect” requires two conditions: biologically meaningful androgen must reach the embryo during the gastrulation window, and embryonic cells must be competent to respond. Evidence for competence includes detection of androgen receptor transcripts in the inner cell mass and undifferentiated mouse embryonic stem cells, with expression increasing during differentiation [1]. This article reviews how testosterone could act directly on gastrulating embryos, distinguishes direct embryonic actions from indirect maternal or placental effects, and highlights the main experimental gaps.