Structure and composition of the oral mucous membrane on the lips and cheeks of the monkey, Macaca fascicularis.

In seven monkeys (6 Macaca fascicularis, 1 M. mulatta; 2.4 +/- 0.6 kg in weight) the labial and buccal mucosae were studied morphologically and quantitatively. Following fixation by perfusion, the upper and lower lips and entire cheeks were dissected free and processed for light-, scanning and transmission electron microscopy. Established programs (HISTOMEP, MUMANA II) and appropriate morphometric techniques were used to estimate, at the light-microscopic level, the epithelial thickness, the width of the combined lamina propria/submucosa, and the volumetric composition of the gland-containing portions of lip and cheek mucosae. The cheek epithelium was more than twofold thicker than the lip epithelium, on the average 0.46 +/- 0.04 and 0.21 +/- 0.02 mm, respectively, with no differences related to sex or topographical sites. The combined lamina propria/submucosa was 1.32 +/- 0.19 and 1.50 +/- 0.26 mm in width in cheeks and lips, respectively. The main mucosal constituents at both sites were glandular and connective tissue, and lymph follicles associated with secretory ducts. In lips, the volume of plasma cells around gland acini correlated positively with the amount of lymphoid tissue present around topographically related ducts. It is suggested that the duct/lymph follicle assembly may serve as a local antigen-recognition system.