[Ultrastructural changes in the intestinal mucosa of children with chronic diarrhea].

Observations were made on biopsied small bowel mucosa by scanning and transmission electron microscopy in 21 infants and children, with chronic diarrhea, their age ranging from 3 months to 24 months, 85.7% of the patients showed various degrees of malnutrition. Ultrastructural changes in the small intestinal mucosa occurred in all of the cases analyzed. The major findings were: (1) villous atrophy; (2) damage to enterocytes, presenting increased extrusion of cytoplasm and enterocytes, with damage of the microvillar surface and degenerative changes of cytoplasm; (3) presence of microorganisms on the mucosal surface; and (4) excessive mucus on the mucosal surface. These results suggest that prolonged mucosal injury, extensive colonization of the mucosal surface by microorganisms, and malnutrition, may be the main causes of chronic diarrhea in children.