Abstract: The histologic features of the large intestine are constant from the ileocecal valve to the anus. From the outer surface inward, the layers that constitute the normal histology of the colon include: serosa, muscularis externa, submucosa and mucosa. The serosa contains small pendulous protuberances of adipose tissue called appendices epiploicae. The muscularis externa is composed of an inner circular muscular layer and an outer longitudinal muscular layer gathered into three thick bands known as teniae coli. The submucosa contains lymph nodes that are especially abundant in the vermiform appendix. The mucosa is flat and presents small holes that correspond to the openings of straight long tubular glands formed by crypts of Liberkuhn. Structurally, the mucosa is formed by a simple columnar epithelium along the lamina propia and a thin muscular layer known as muscularis mucosae. Although the epithelium that covers the luminal surface and the crypts is of the same type, the cytologic distribution has some unique patterns. Mature absorptive cells and globet cells formed the luminal surface epithelium while the epithelium lining the crypts consists of undifferentiated precursor cells, immature absorptive cells, globet cells, and enteroendocrine cells. Enteroendocrine cells are interspersed among other nonendocrine epithelial cells and are generally located in the deepest portions of the crypts.
Publication Year: 2003
Publication Date: 2003-01-01
Language: en
Type: article
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