The differentiation, architecture and function of the mucosa of the digestive tract is the result of close interactions between the epithelial cells and their underlying connective tissue. This interaction not only plays a role in the normal morphological organization of the intestinal mucosa but also in the organization and maturation of the enterocytes, the development of some of their enzymatic activities, the transport of nutrients and the restitution of the epithelium following denudation of the surface of villi due to loss of enterocytes. It is thought that disturbances of the cells of the connective tissue, especially of the myofibroblasts as well as of some of the above mentioned mechanisms, participate in the pathogenesis of some gastrointestinal diseases, celiac disease among them. This review summarizes some of the knowledge in this area.