The duodenal mucosa in health and disease. A clinical and experimental study

Normal Human Duodenal Mucosa. There are three clearly identifiable different histologic types of normal human duodenal mucosa. These have been termed antral type-duodenal mucosa, transitional-type duodenal mucosa, and jejunal-type duodenal mucosa. The mucosa has a characteristic fingerlike distribution at the gastroduodenal junction. Transitional-type duodenal mucosa, one of the three types of normal mucosa, is also referred to as gastric epithelium or gastric surface epithelial metaplasia. Evidence is presented to support the view that this is a normal finding and is not an indication of duodenitis. Normal variations of villi are described, which again cannot be regarded as indicators of duodenitis. The normal shape and mucosal lining of the pyloric sphincter are described. Abnormal Duodenal Mucosa. Acute and chronic duodenal ulcers occur in jejunal type duodenal mucosa. It is suggested that the three different types of mucosa vary in their degree of susceptibility to the effect of acid hypersecretion. Aspects of the diagnosis of duodenitis are reviewed. Duodenitis and gastritis both are patchy conditions, which may persist or become worse in spite of ulcer healing. Without the availability of accurate morphometric methods and quantitative immunocytochemistry, the classification suggested by Jenkins et al has much to recommend it. When the Jenkins classification was used in giant duodenal ulceration, there was widespread duodenitis, which was not seen in conventional duodenal ulceration. Chronic duodenitis does not appear to be related to chronic duodenal ulceration as chronic gastritis is related to chronic gastric ulceration. Regeneration of Duodenal Mucosa. The Brunner glands as well as the crypts of Lieberkühn appear to regenerate from cells in the base of these crypts, where there is a marked increase in mitotic activity. It is rare to see mitotic activity in normal or regenerating Brunner glands. Surface epithelium regenerates from adjacent normal villi, not from the Brunner glands.