endodermal

Endodermal is an adjective referring to the endoderm, the innermost of the three primary germ layers formed during early embryonic development in animals. The endoderm gives rise to the lining and internal structures of the gut and its associated organs, and it contributes to certain glands and tissues involved in digestion and metabolism.

In animals, endodermal derivatives include the epithelium of the gastrointestinal tract from the esophagus to the anus, the epithelium of the respiratory tract, and the ducts and secretory cells of several glands such as the liver, pancreas, and biliary system. It also lines portions of the urinary bladder and other internal surfaces. Some organs, including the thyroid, parathyroids, and thymus, have endodermal origins via contributions from pharyngeal pouches, with endodermal tissue playing a key role in organogenesis. The formation of endoderm is regulated by transcription factors such as Sox17 and FoxA2 and involves signaling interactions with mesodermal tissue during gastrulation.

In plants, the term endodermal can describe tissues related to the endodermis, a single layer of cells surrounding the vascular cylinder in roots and sometimes stems. Endodermal cells regulate the radial movement of water and minerals through the Casparian strip, a barrier enriched with suberin and lignin that helps control uptake into the stele.

Clinical relevance includes congenital anomalies arising from disrupted endoderm development and endodermal tumors, such as yolk sac tumors, which reflect the diverse developmental potential of endodermal derivatives.