Infection by spirilla in the stomach of the rhesus monkey.

Light and electron microscopy showed gastric spirilla in the gastric mucosa of 45 clinically normal rhesus monkeys (Macaca mulatta). In paraffin sections, gastric spirilla were best shown by silver impregnation stains. When stained by hematoxylin and eosin (HE), gastric spirilla may be mistaken for strands of mucus. In thick sections of epon-embedded tissue, gastric spirilla looked like "corkscrews" with up to 12 coils. They were 8 microns long and 0.7 micron wide, and had characteristic bipolar flagella. They were concentrated in the gastric glands at the isthmus, were less common at the neck and base, and were absent in the gastric lumen. Gastric spirilla were associated closely with parietal cells and could penetrate their cytoplasm. Gastric spirilla elicit neither changes of host cytocomponents nor an inflammatory response in the gastric mucosa.