PROLIFERATION KINETICS IN EPITHELIUM OF GUINEA-PIG COLON III. DISTRIBUTION OF BLOOD CAPILLARIES ALONG THE CRYPT

The colonic blood vessels of the guinea-pig were infused with carmine-gelatine and the occurrence along the crypt of mucosal capillaries containing the dye was examined. The pattern of capillary distribution along the crypt is inhomogeneous but is similar for short, medium and long crypts. Capillaries occur least frequently at the bottoms of crypts, that is within the lowest 0.05% of the crypt length. The frequency rises significantly between 0.05 and 0.40 of the crypt length; this rise is accompanied by an increase in the number of DNA-synthesizing cells. A significant fall in capillary frequency along the crypt between 0.35 and 0.45 of crypt length coincides with the beginning of a decrease in the number of DNA-synthesizing cells. The highest frequency of capillaries occurs in the upper 0.20 of the crypt length and beneath the lining epithelium.