Özet:

Different dynamic processes and numerous molecular mechanisms play a role in the body development process. Gastrulation, which occurs in the 3rd week of embryonic development, is the process of formation of the trilaminar germ disc from the bilaminar germ disc. Gastrulation is also a process that determines the formation of body axes. The formation of body axes is very important for embryonic development. Before and throughout gastrulation, the anteroposterior (AP), dorsoventral (DV) and left-right (LR) body axes are formed. There are two signaling centers in the mammalian embryo, one in the primitive node and the other in the anterior visceral endoderm (AVE). The primitive node expresses Nodal, Chordin, and Noggin, while the AVE expresses several genes (OTX2,LIM1, and HESX1) required for head formation. Nodal, a member of the TGF-β family, is the main regulator of primitive line and mesoderm formation and is very important for axis formation in embryonic development. The primitive streak expresses transcription factors and many specific genes. BMP, expressed by the primitive node, has an important role in the formation of the dorsal part of the body. Right-left asymmetry begins with cell-cell interactions that occur in the primitive node during gastrulation. Pitx 2, the transcription factor that is a major determinant of the left side, is strongly expressed on the left side. Another important genes on the left side are Lefty 1 and Lefty 2, which are members of the TGF-β family. In research to date, the genes that control the development of the right side of the embryo are not as well defined as those on the left side. In this review, how the body axes (anterior-posterior, dorsal-ventral and left-right) are formed during embryonic development and the signaling molecules involved in this development are explained.

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