Scanning electron microscopical observation on the isolated mucosa of rat small intestine: with special reference to the intestinal crypt.

The small intestinal mucosa of rats (male, aged 8 weeks) was isolated by the Bjerknes and Cheng's method (1981): the anesthetized rats were perfused through the left ventricle with a solution of ethylenediaminetetraacetic acid (30 mmol/l) in calcium-magnesium-free Hanks' solution, and then the mucous epithelium was removed from a segment of the duodenum, jejunum and ileum by means of vibration. Three-dimensional images of crypts on the isolated mucosa were obtained by scanning electron microscopy. The length and number of the crypts between the villi were observed to decrease along the intestine from the duodenum to the ileum. The majority of intestinal crypts were simple non-branched tubular glands, however, budding and bifurcation of the crypt ends were often observed. It was relatively rare to find longitudinally split crypts. The shapes of the crypts seems to denote various stages of the proliferation of crypts.