Enterozyten

Enterozyten, or intestinal enterocytes, are the predominant absorptive cells that line the mucosal surface of the small and, to a lesser extent, the large intestine. They arise from intestinal stem cells in the crypts of Lieberkühn, migrate along the crypt-villus axis, and differentiate into mature absorptive cells. Their turnover is rapid, with renewal occurring over a few days.

anatomically, enterocytes are tall columnar cells equipped with a highly organized apical brush border composed of densely packed microvilli. This structure increases surface area for absorption and houses various digestive enzymes. The cells display epithelial polarity, with distinct apical and basolateral membranes and tight junctions that form a selective barrier to paracellular transport.

functionally, enterocytes perform nutrient and fluid absorption. Carbohydrate uptake involves the SGLT1 transporter on the apical membrane and GLUT2 on the basolateral side, while amino acids are transported by specific amino acid transporters. Peptide absorption occurs via the peptide transporter PEPT1. Lipid digestion products are absorbed as fatty acids and monoglycerides, reassembled into triglycerides, and packaged into chylomicrons for release into the lymphatic system. Enterocytes also absorb vitamins and minerals, including calcium and iron, and participate in bile acid reabsorption in the distal ileum. Brush-border enzymes, such as lactase and sucrase-isomaltase, facilitate final digestion at the luminal surface.

in addition to absorption, enterocytes contribute to barrier function and immune interaction. Tight junctions restrict paracellular flow, and enterocytes participate in mucosal immunity through antigen sampling and, in some contexts, transcytosis of immunoglobulins.

disruption or loss of enterocytes occurs in conditions such as celiac disease and inflammatory bowel disease, leading to impaired absorption and barrier dysfunction.