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 Hellman2 expressed the belief that they are "activity" centers where lymphocytes are destroyed.
KELEMEN G. PATHWAY OF THE TONSILLAR LYMPHOCYTE. Arch Otolaryngol. 1943;38(5):433–444. doi:10.1001/archotol.1943.00670040452003
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