Distribution of microspheres with different diameters in the small bowel wall of the cat.

The purpose of the present study was to investigate the distribution in the small bowel wall of intracardially injected microspheres with different diameters, and to find a sphere size that could be used for determination of blood flow to the different layers of the bowel wall. Microspheres were injected into the left ventricle of the hearts of cats in the following order of succession, 8--10, 15 +/- 5, 25 +/- 5 and 50 +/- 5 micrometer. Samples of the proximal part of the jejunum and the distal part of the ileum were examined microscopically, and the size and the location of the spheres recorded. The following distribution of the microspheres was found: villi 6--16 micrometer, crypt layer 6--20 micrometer, propria below the crypts and the muscularis mucosa 11--24 micrometer, submucosa 9--66 micrometer and muscularis 6--30 micrometer. Spheres between 8 and 13 micrometer appeared to be fairly uniformly distributed in the different layers of the intestinal wall.