Ultrastructural changes in the lysosomes of rachitic intestinal absorptive cells

In chicks maintained on a rachitogenic (vitamin D deficient) diet, the number of intestinal absorptive cell calcium-lysosomes is markedly decreased in comparison to normal animals. In addition, the majority (better than 50%) of these rachitic calcium-lysosomes are atypical in their fine structure resembling the lamellar bodies seen in certain diseases (Tay-Sachs disease, Duchenne's muscular dystrophy). Such atypical organelles are characterized by their internal membranous swirls reminiscent of myelin figures. This information appears to be a further indication that lysosomes are normally involved in calcium homeostatic mechanisms and therefore sensitive to circulating vitamin D levels.