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Sustained hypomyelination and high serum thyroid hormone in aged black tremor hamster
2003
Kim, H.O. (Hokkaido Univ., Sapporo (Japan)) | Kimura, T. | Ochiai, K. | Yazawa, H. | Itakura, C. | Umemura, T.
Oligodendrocytes and myelin in the corpus callosum of black tremor and normal hamsters aged over 1.5 years were ultrastructurally examined to determine the myelination index (ratio of myelin thickness/diameter of axon), percentage of naked axons, and proportions of oligodendroglial subtypes (light, medium and dark). The mutant hamsters were remarkably hypomyelinated, with a low myelination index and a high proportion of naked axons, and high proportions of the dark subtypes. Serum concentrations of thyroid hormones (T sub(3) and T sub(4)) in 6-week-old mutant hamsters were 2-fold (T sub(3)) to 3-fold (T sub(4)) higher than those of age-matched normal animals. However, in the aged animals (over 1.5 years old) only T sub(4) levels of the mutant hamsters were higher in the mutant than normal hamsters. The black tremor hamsters were hypomyelinated throughout their life and high serum level of thyroid hormones might have played a role in the hypomyelination.
Mostrar más [+] Menos [-]Ventricular dyssynchrony as a cause of structural disease in the heart of Dorper sheep
2004
Ker, J. (Pretoria Univ., Gezina (South Africa). Physiology Dept.) | Webb, E.C. | Van der Merwe, C.F.