The structure of the palatine tonsils in an evolutionary line of mammals and its development in man was studied. The homologies between the thymus and tonsils were pointed out. Both primordia come from the same source and their epithelium reticulizes and can form concentric corpuscles. The tonsil develops from a doubled primordium and consists of two lobes. Attention is drawn to the close relation between tonsils and glands. In the evolution the glands diminish and more crypts are formed. After antigenous stimulation, proliferation of the crypt epithelium takes place which provokes the increase of venules. They bring new populations of lymphoid elements which penetrate into the reticulated epithelium and finally form new follicles.

Department of Histology and Embryology Faculty of Medicine Charles University Plzen Czechoslovakia