Bernard's1 observations of venous blood acquiring the redder tint of arterial blood during active digestion served to focus notice upon the likely presence of arteriovenous communications in the gastric mucosa. Since this initial observation, several reports have attested to the presence of the arteriovenous shunts in the stomach in all layers except the mucosa.2,3 The diameter of these arteriovenous shunts has been assessed by determining the size of nonradioactive microspheres that pass from the arterial to the venous side of the gastric microcirculation. In 1950, Walder4 injected glass microspheres, ranging in size from 40μ to 200μ, into the gastric arterial circulation of a resected part of a stomach from humans who had undergone a partial gastrectomy. The maximum size of the spheres that passed from the artery to the vein was 140μ in diameter. Glass spheres of similar size (100μ to 180μ) were recovered in veins draining