Nonuniform horizontal and vertical distributions of immunoglobulin A cells in canine intestines

The horizontal and vertical distributions of immunoglobulin (Ig) A cells were determined in canine intestines by immunoperoxidase assay on formalin-fixed, paraffin-embedded tissues. With this technique, excellent preservation of tissue morphology was obtained, and special tissue fixation and handling were not required. Immunoglobulin A cells were counted in 2-different ways at different magnifications. It was seen that (i) the duodenum usually had the highest cell counts at all levels of the lamina propria, (ii) IgA cells in the zone closest to the intestinal lumen became less numerous caudad from the duodenum to the colon, (iii) the zone closest to the submucosa (zone D) had the fewest IgA cells in the small intestines, and (iv) the IgA cell counts in zone D tended to be lowest in the jejunum and ileum and highest in the duodenum and colon.