ALDH1A2 and myeloid sarcoma: The presence of reduced but viable OPCs, and decreased oligodendrocytes in the lesions of Raldh2 deficient mice resembled the pathology of chronic MS lesions, which often display variable number of OPCs, and a severe deficiency in oligodendrocytes and remyelinated axons (Chang et al., 2000; Wolswijk, 2000).