In this country alone, defective endoderm development results in 3,400 children a year being born with congenital gastrointestinal malformations. 

Examples of diseases affecting endodermal organs, such as the pancreas, biliary system and intestine, include juvenile diabetes, biliary atresia and Crohn’s disease. Surprisingly little is known about how early endoderm cells obtain positional identity along the anterior-posterior (A-P) axis, or how this regional identity lays down the blueprint for where organs will form in the developing gastrointestinal and respiratory tracts. 

After gastrulation in mice (7.5 days after fertilization), the endoderm is a one-cell-layer thick sheet of approximately 500-1,000 cells that will form the epithelial lining of the esophagus, lungs, stomach and intestines, and is a major component of many glands including the thyroid, thymus, pancreas and liver. Some endodermal functions include glucose homeostasis, gas exchange, taste, digestion, nutrient absorption, detoxification, blood clotting and hematopoiesis. 

A better understanding of endoderm development has proven seminal for discovery of molecular diagnostics of birth defects and for recent advances in directing stem cell differentiation into pancreas, liver and intestinal tissue.