Crypt architecture of tonsilla lingualis in the monkey, Macaca fascicularis. A correlated light- and scanning electron-microscopic study.

Crypts of the lingual tonsil were investigated in 10 male and female Macaca fascicularis by use of correlated light- and scanning-electron microscopy. Counting of crypt openings provided an estimate of the total number of respective crypto-lymphatic units, which were found to range from 20 to 39. Crypt openings appeared in three distinct morphological varieties, i.e. circular, oval or slit-like. Tonsillar units existed individually or were arranged in a rosary fashion below a slit-like mucosal fold serving as a common exit. Although the crypt epithelium was generally non-keratinized, individual cells showing a surface pattern similar to that of the keratinized cells could be encountered. The crypt epithelium was frequently fragmented and showed heavy mononuclear cell infiltration and surface discontinuities, with lymphoid cells coming in contact with luminal contents. The crypt lumen either appeared as a simple epithelial invagination or existed as a complex, cavernous pouch with many blind-ending diverticula. The lumen contained a mixture of exfoliated epithelial cells, leucocytes and bacteria. The secretory ducts of the posterior lingual glands opened occasionally at various levels into the crypt lumina or independently to the exterior.