Histochemical demonstration of ornithine transcarbamylase activity in fetal liver

A histochemical technique for demonstrating ornithine transcarbamylase (OTC) activity in human and rhesus monkey fetal liver is described. The proportion of OTC-positive cells increases in fetal monkey liver between 130 and 150 days of gestation. The histochemical assay can be used to verify the prenatal diagnosis of OTC deficiency in the human fetus.