Lipid storage in liver from 20 week-old foetuses with Niemann-Pick type A (NPA) (3 cases) and type C (NPC) (3 cases) diseases. This was compared to concentrations in foetuses with lysosomal disorders not affecting the liver (controls, 5 cases). All results are expressed as mean values for each group. In NPA, the primary stored lipid, sphingomyelin, is already very elevated, and is accompanied by a prominent secondary increase of cholesterol. In NPC, massive cholesterol storage occurs, with a modest sphingomyelin increase.