A method for observing the gastric microcirculation directly in the living animal and the results of its application to the study of the rat gastric microcirculation are described. The exteriorized stomach of an anesthetized rat was transilluminated by a cool light transmitted from a high intensity light source by means of a quartz rod. Illumination was adequate for direct microscopic visualization of blood flow through the muscle layer. After a portion of muscle and serosa had been dissected carefully, blood flow could be traced through the rich submucosal network of arterioarterial anastamoses down to the mucosa and back through collecting veins, emerging from the mucosa to the submucosal venovenous anastamotic network. By everting and transilluminating the exteriorized stomach, the superficial mucosa was visualized and blood flow could be traced through the hexagonally distributed capillaries surrounding the gastric glands to the collecting veins. The distribution of vessels in each of these layers is described in detail. Despite a careful search, no arteriovenous anastamoses were found, either in the submucosa or in the superficial mucosa.

A method for the in vivo microscopic study of the rat gastric microcirculation is described. Two preparations were used: the exteriorized stomach to study the serosal, muscular, and submucosal circulation (the latter following careful dissection of the serosa and submuxcosa) and the inverted pouch to study the superficial mucosal circulation. The preparations were transilluminated utilizing a high intensity light source and an intragastric quartz rod light carrier. The gastric microvessels and their blood flow could be readily followed through all layers of the stomach except the deep mucosa.

A high and consistent incidence of gastric lesions occurs in rats exposed to combined cold and electrostress for 12 hr. The electric stimulus was delivered through the grid of the cage floor consisting of alternately charged bars. The rats maintained a stiff, motionless posture with tight grip on the bars for the greater part of the experiment. In this way the animal apparently avoided intermittent shock, although the circuit was permanently closed by its feet, which made the current flow through his body continually. In a series of experiments designed to analyze the psychologic stress content of this experimental situation, the rats were able to avoid electric current altogether by escaping onto an insulated platform placed on the floor of the cage. Under these conditions, ulcers still developed which may be attributed largely to a psychologic factor. The cold electrostress-induced gastric lesions were prevented by atropine sulfate, atropine methyl nitrate, and propantheline. Of the central depressants tried, only chlorpromazine reduced the incidence of lesions when given in a low dose; the incidence was higher after a large dose. Meprobamate, phenobarbital, pentobarbital, and chlordiazepoxide were ineffective.