Intralysosomal cystine crystals in cystinosis.

Electron microscopic study of conjunctival biopsies from members of one sibship each of nephropathic and benign cystinosis showed polymorphic cystine profiles abundantly distributed in fibroblasts and histiocytes. These crystalline spaces measured from 0.2(i to 2/i and were delineated marginally by intact cellular membranes. Small crystalline aggregates were found in acid-phosphatase-positive osmophilic dense bodies and they appear to be the earliest manifestation of intracellular deposition of cystine. This study suggests that there are striking morphologic similarities in the tioo forms of cystinosis at the cellular level and. supports the suggestion that both may represent disorders in cystine metabolism by a subcellular organelle of lysosomal type.