Ultrastructural changes of zinc deficient rat epidermis: an electron microscopic study

Zinc deficiency was produced in rats by feeding them a diet containing 0.5 mg zinc per kg. After 2 weeks the zinc-deficient rats showed markedly stunted growth as compared with control rats receiving an identical diet supplemented with 50 mg zinc per kg. After about 3 weeks all rats in the zinc-deficient group developed a greasy, coarse and scaly coat with dispersed, denuded, eczematous patches. After 32 days the animals were sacrificed and skin specimens were obtained from the abdominal area. Electron microscopy showed two different patterns of epidermal changes: (A) edematous cell bodies and cell organelles, degenerate nuclei, while desmosomes were well preserved: (B) parakeratotic and dyskeratotic cells with sparse keratohyalin granules, abnormal keratinosomes, poorly developed desmosomes, and disintegrated mitochondria in the upper part of the epidermis. In the lower part, keratinocytes contained numerous ribosomes and thick chromatin aggregates in the nuclei. Dendritic cells were disintegrated in pattern A, while they appeared normal in pattern B. In both patterns mitochondria showed vacuoles and a lack of DNA granules. A transient form of type A and B changes was also observed.