Myelin acquisition in the central nervous system of the mouse revealed by an MBP-Lac Z transgene

• Published in: The Journal of neuroscience Vol. 12; no. 12; pp. 4890 - 4897
• Main Authors: Foran, DR, Peterson, AC
• Format: Journal Article
• Language: English
• Published: Washington, DC Soc Neuroscience 01.12.1992; Society for Neuroscience
• Subjects: Animals; beta-Galactosidase - biosynthesis; beta-Galactosidase - genetics; beta-Galactosidase - metabolism; Biochemistry and metabolism; Biological and medical sciences; Brain - physiology; Brain - ultrastructure; Central nervous system; Escherichia coli - enzymology; Escherichia coli - genetics; Fundamental and applied biological sciences. Psychology; Genes, Bacterial; Mice; Mice, Transgenic; Myelin Basic Protein - biosynthesis; Myelin Basic Protein - genetics; Myelin Sheath - physiology; Myelin Sheath - ultrastructure; Oligodendroglia - physiology; Oligodendroglia - ultrastructure; Optic Nerve - physiology; Optic Nerve - ultrastructure; Organ Specificity; Recombinant Proteins - biosynthesis; Recombinant Proteins - metabolism; Spinal Cord - physiology; Spinal Cord - ultrastructure; Vertebrates: nervous system and sense organs; Enzyme; Myelin; Rodentia; Central nervous system; Transgenic animal; Neuroglía; β-D-Galactosidase; Postnatal development; Vertebrata; Mammalia; Enzymatic activity; Oligodendrocyte; Mouse; Myelinization
• ISSN: 0270-6474; 1529-2401
• DOI: 10.1523/jneurosci.12-12-04890.1992

Myelin has pronounced effects upon the morphology, function, and growth of axons in the mammalian CNS. Consequently, oligodendrocyte development and myelination have been investigated using a wide variety of histological, immunocytochemical, ultrastructural, and biochemical techniques. While many of the spatial and temporal features of myelin appearance have been characterized, for any one species only limited regions of the CNS have been investigated. To address this limitation, we have derived transgenic mice in which the bacterial Lac Z gene is regulated by promoter elements of the myelin basic protein gene. When differentiating oligodendrocytes begin to elaborate recognizable myelin, they initiate expression of the MBP-Lac Z transgene and accumulate readily detectable levels of beta-galactosidase. Here, we exploit the sensitivity, resolution, and ease of beta-galactosidase histochemical assays to characterize the temporal and spatial patterns of CNS myelination in the mouse. Many features of the myelination program revealed by this approach were predicted by the immunocytochemical and ultrastructural data derived from other species. Nonetheless, previously undocumented patterns were also encountered. beta-Galactosidase was expressed first by oligodendrocytes in the ventral spinal cord, 1 d prior to birth. There, myelination proceeded in a strictly rostral-caudal direction, whereas in the dorsal cord, myelination initiated in the cervical enlargement and proceeded in both rostral and caudal directions. In the cerebellum, deep regions myelinated first, and in the optic nerve, myelination initiated at the retinal end. In contrast, the lateral olfactory tracts, pons, and optic chiasm initiated myelination along their entire course.