Ultrastructural studies on Paneth cell apoptosis in zinc deficient rats

An ultrastructural study into the origins of the increased number of apoptotic bodies in the small intestinal crypts of zinc deficient rats was carried out. Two strains of rat were used and each strain was sub-divided into three groups; zinc deficient, pair-fed controls and ad libitum controls. All three groups of one strain were heavily infested with intestinal parasites, both bacteria and flagellated protozoa. Increased numbers of apoptotic bodies were found in the upper crypt/villus region of zinc deficient rats in both the parasitized and parasite free strains. Some of these apoptotic bodies contained structures resembling the electron lucent intestinal epithelial cells found in zinc deficient rats, others contained unidentifiable cell remnants that had undergone advanced degenerative changes. In zinc deficient parasitized rats only, apoptotic bodies were found at the crypt base which contained identifiable remnants of Paneth cells. The majority of these had been ingested by intestinal epithelial cells but some had been ingested by macrophages. The effect of zinc deficiency and parasitic infestation on apoptosis is discussed.