Oligodendrocytes from jimpy and normal mature tissue can be 'activated' when transplanted in a newborn environment.

Fragments of corpus callosum from P13 normal and jimpy (jp) mutant mice (containing only postmigrating precursors and differentiated oligodendrocytes (ODCs, some of them myelinating soon) have been transplanted into the thalamus of newborn shiverer (shi) mutant mice. The behaviour of transplanted ODCs has been assayed by immunohistochemistry of their myelin basic protein (MBP)-positive myelin synthesized in the host shi brain whose myelin is deprived of this component. ODCs and postmigrating precursors contained in P13 normal corpus callosum survived, migrated out of the graft and myelinated in the shi host parenchyma. The high ratio of positive cases observed was comparable to the one observed in previous experiments using fragments of newborn or embryonic normal tissue. When fragments of jp tissue were used as donors, postmigrating jp ODCs or precursors migrated on long distances out of the graft and synthesized large amounts of myelin as estimated by the size of the MBP-positive myelin patches present in the host shi brain. The extent of migration and the size of these myelin patches were more important than those observed in previous experiments using fragments of newborn or embryonic jp CNS as donors. By contrast, the low ratio of positive cases observed suggested that the survival of P13 jp ODCs or their postmigrating precursors cannot be restored by the newborn shi environment.(ABSTRACT TRUNCATED AT 250 WORDS)