In embryonic life, as soon as lymph cells accumulate around the crypts, which are hollowed out from endodermal buds of the second branchial pouch as a primordium of the tonsil, they penetrate into the lumens of the crypts, passing through the epithelium, with reticulization of the latter. This manifestation of lymphocytic activity continues until the last vestige of the tonsil disappears, on completion of its involution. This transfer of lymphocytes commences before the lymphoid tissue around the crypts differentiates into secondary nodules, and the process continues throughout the period of regression, after the nodules have disintegrated, only residual accumulations of lymphocytes being left around the remnants of the crypts. Many phases of this activity still remain controversial questions. For example, in the parenchyma, the clear centers of the secondary nodules represent "germinal" tissue according to Flemming,1 whereas Hellman 2 expressed the belief that they are "activity" centers where lymphocytes are destroyed. In the epithelium, some observers believe that they can follow the various white blood cells, including lymphocytes, in their course through all the epithelial strata, whereas others think that these cells are destroyed within the layers of the epithelium. Also, some investigators hold that the penetration of lymphocytes takes place only in the deep portions of the crypts, whereas others believe it occurs throughout their entire extent. Moreover, some are of the opinion that once the lymphocytes have reached the lumen of a crypt they die, whereas others assert that they are conveyed along the lumen of the crypt to the surface of the tonsil, where they become transformed into salivary corpuscles.The aim of the present paper is to offer a brief account of the successive steps in the life history and ultimate fate of the tonsillar lymphocyte. My own observa¬ tions, both previously published and recent, are correlated with known facts, as established by other workers, in order to arrive at as fully integrated a picture as possible.
MATERIAL AND METHODSIn the present study, human tonsils which were removed at operation were fixed in a 10 per cent concentration of solution of formaldehyde U. S. P. Subsequently, they were embedded in paraffin and sectioned. The sections were prepared by three methods : (a) hematoxylin and eosin stain ; (b) Maximow's azur II stain, and (c) Gömöri's method of impregnation with ammoniacal silver hydroxide.The reticular framework of the diffuse tonsillar parenchyma was demonstrated in three ways. In previous investigations, Kelemen and Hasskó,3 instead of using the technic of
