29- Integration of External Coelom into Internal Coelom

The integration of the external coelom into an internal coelom is a fundamental process in embryonic development, beginning with the formation of the peritoneum. The latter develops in parallel with the neural tube, whose growth is orchestrated by the fluid reorganization of the embryo. The establishment of the primitive aortas plays a central role in this mechanism, promoting a return towards the midline of the embryo. The formation of the amniotic and vitelline cavities, as well as the development of the primitive digestive tube, are key stages in this integration, allowing the creation of intraperitoneal fluid.

As this evolution progresses, the peritoneum, which is derived from the mesoderm, acquires metabolic, protective, and mechanical functions. It is essential for the motility and mobility of peritonealized organs. Furthermore, specialized mesothelial cells within the peritoneum allow inter- and intra-peritoneal communication, thus facilitating the integration of environmental information. This process is crucial for the development of the holobiont, which integrates genetic and environmental elements, thus influencing the genetics and epigenetics of the individual, and highlighting the importance of an adequate environment for evolution and adaptation.