Myelination in the CNS of mld mutant mice: comparison between composition and structure.

Myelination was studied between 15 and 135 days postnatally in the brain and optic nerves of myelin deficient (mld) mutant mice. Between 15 and 30 days almost no myelin basic protein (MBP) could be detected in mld myelin. The axons were loosely wrapped by membranes which only fused at the extracellular sites forming the intraperiod line.

Anticonvulsive treatment of myelin-deficient (mld) mice improves survival and confirms the delayed increase of myelin basic protein.

Myelin-deficient (mld) mutant mice were treated with phenobarbital between 60 and 90 d of age. The survival rate at 90 d increased from 1.4% in untreated mutants to 46% in those who received phenobarbital.

In vitro myelin basic protein synthesis in the PNS and CNS of myelin deficient (mld) mutant mice.

The CNS of the mutant mld has a severe myelin deficit. In contrast, myelination is normal in the PNS. Previous studies showed that myelin basic proteins (MBP) are practically missing in mld CNS and PNS tissues.

Myelin basic protein deficit in the PNS of mld mutant mice recovers during development.

Myelination was studied between 15 and 135 days postnatally in peripheral nerves of myelin deficient (mld) mice and in unaffected littermates. The nerve weights were not affected by the mutation and showed a 4-fold increase during the developmental period studied. The amounts of myelin present in peripheral nerves, as shown by biochemical and morphological techniques, were slightly reduced in mld in comparison to control mice.

Density distribution of 2?,3?-cyclic nucleotide 3?-phosphodiesterase and myelin proteins in particulate material from myelin deficient (mld) mutant and control brains.

Total particulate material from control and myelin deficient (mld) brains was subjected to density centrifugation on a continuous sucrose gradient. Particles from control brains distributed in a bell-shaped mode with a peak density near 0.64 M-sucrose.