AbstractThe storage of glycosaminoglycans (GAGs) within cells of the central nervous system of dogs with mucopolysaccharidosis I (MPS I) was studied. Lectins that detect these stored GAGs were applied to formalin fixed tissues from 5 MPS I-affected dogs, 2 of which were previously treated by littermate bone marrow transplantation (BMT), and from 2 unaffected littermate controls.In all transplant recipients there was reduced reactivity of the central nervous system (CNS) neurons with soybean agglutinin and horse gram agglutinin indicating that BMT results in reduced levels of those GAGs stored excessively in MPS I. Wheat germ agglutinin was found to react less strongly with cells from treated or untreated dogs despite its predicted binding to sugars in GAGs that are known to accumulate in MPS I. These findings, coupled with previously reported total brain GAG content, show that neuronal storage of GAG is reduced following BMT in canine MPS I. (The J Histotechnol14:183, 1991)