lacteales

Lacteales are the lymphatic capillaries within the villi of the small intestine. In anatomical literature, the plural form lacteales is used to refer to all such vessels. They are part of the mucosal lymphatic network and are specialized to absorb dietary lipids.

Structure and location: Lacteals reside in the lamina propria of the intestinal villi, with each villus containing a central lacteal. The endothelial lining is designed to permit uptake of lipids, and the vessels connect to the submucosal lymphatic network. They are typically blind-ended and contain valves to help regulate lymph flow.

Physiology and function: After fats are emulsified and absorbed by enterocytes, long-chain fatty acids are re-esterified and packaged into chylomicrons. These large particles enter lacteals as chyle and are transported through the lymphatic system to the cisterna chyli and then the thoracic duct, enabling lipid transport while bypassing the hepatic portal circulation.

Drainage and circulation: Lacteales drain into the intestinal lymphatic trunks, pass to the cisterna chyli, and onward through the thoracic duct into the systemic circulation. Valves and surrounding smooth muscle aid in lymph propulsion.

Clinical significance: Disorders affecting intestinal lymphatics, including intestinal lymphangiectasia, can lead to fat malabsorption and protein-losing enteropathy. Secondary obstruction from infection, inflammation, or neoplasia can also impair lipid absorption and cause edema or nutritional deficiencies. Rarely, chyle leaks or lymphatic abnormalities involving lacteales can occur.