Developmental relation between palatine tonsils and kidney.

The evolutionary changes of the immune process in the whole line of representatives of the organisms were followed. The immune organs responsible for processing the antigens evolved from the derivatives of coelomic lining over the gut folds to the immune organs developed in the gill region of the digestive tract. Among them the tonsils have to be considered as a very modern evolutionary immune organ. They develop also as the latest in ontogeny even though their primordium contributes very early to the IgA production. The results of the host-antigen reactions have to be eliminated by the excretory organs, which are in invertebrates represented by body poruses and various types of simple segmentally arranged nephridia which are in contact with the gills. These nephridia have evolved in lower vertebrates in pronephros, further in mesonephros and finally in kidneys with filtrating nephrons. In case of defective elimination, the more voluminous immunocomplexes can form the subendothelial or mesangial deposits.