Abstract
The liver of a 19-year-old woman with argininosuccinase deficiency was studied ultrastructurally under conditions for excellent tissue fixation. Dilated smooth endoplasmic reticulum and mitochondrial crystalloids were the most prominent abnormalities found. These features were compared to fine-structural abnormalities found in other disorders of the Krebs-Henseleit pathway. No change was considered specific or related to subcellular enzyme localization.