enterocyten

Enterocyten, or enterocytes, are the predominant absorptive cells lining the villi of the small intestine. They originate from stem cells in the crypts of Lieberkühn and migrate upward to form a continuous epithelium. Mature enterocytes are tall columnar cells with a densely folded apical brush border of microvilli, which increases surface area for digestion and absorption. The brush border houses enzymes such as lactase, sucrase–isomaltase, and maltase–glucoamylase, which complete luminal digestion, and various peptidases that process peptides.

Functionally, enterocytes transport nutrients from the intestinal lumen into the bloodstream or lymph. On the apical membrane, transporters include SGLT1 for glucose and galactose, GLUT5 for fructose, and PEPT1 for di- and tri-peptides; on the basolateral side, GLUT2 and other carriers transfer sugars, amino acids, lipids and micronutrients into the circulation. Lipid absorption involves micelles and the assembly of lipoproteins for export. Enterocytes also contribute to barrier function through tight junctions, protecting against pathogens while allowing selective absorption.

During renewal, enterocytes are replenished from crypt stem cells, with a turnover time of roughly 3–5 days. Impairment of enterocyte function or integrity underlies many gastrointestinal disorders, including malabsorption syndromes and conditions such as celiac disease and infections. Overall, enterocytes play a central role in nutrient uptake, barrier maintenance, and mucosal signaling in the small intestine.