The functional evolution of GALT: a review

This synopsis of the evolution of gut-associated lymphoid tissue (GALT) in increasingly complex animals suggests that GALT plays an essential role in cellular nutrition and energy metabolism as well as in immunity. Throughout phylogeny, the mediation of immunity as well as cell nutrition depends on the normal capacity of GALT to produce lymphocytes which customarily generate an evolving variety of soluble globulins during maturation and proceed to migrate throughout the body as emperipoletic cytoplasm-depleted cells which donate their residual constituents to genetically compatible cells; and destroy living matter recognized as genetically incompatible. A dividend is that the lymphocytes not only destroy the genetically foreign but also render the remains innocuous or useful as food.