Glial tubes

Peretto P, Meriglii A, Fasolo A, Borifariti I (1997) Glial tubes in die rosti al migi atory stream of die adult rat. Brain Res Bull 42 9—21. 

Schmidt-Lantermann clefts are structures where the cytoplasmic surfaces of the myelin sheath have not compacted to form the major dense line and therefore contain Schwann or glial cell cytoplasm (Fig. 4-9). They are common in peripheral myelin but rare in the CNS. These inclusions of cytoplasm are present in each layer of myelin. The clefts can be visualized in the unrolled myelin sheet as tubes of cytoplasm similar to the tubes making up the lateral loops but in the middle regions of the sheet, rather than at the edges (Fig. 4-9). 

Cell adhesion molecules (CAMs) play critical roles in all facets of nervous system development and maintenance. Important phenomena in which CAMs are involved include initial formation of the neural tube and the neural crest, migration of all neurons and glial cells, axonal outgrowth and guidance, target selection, synaptic stabilization and plasticity, myelination and nerve regeneration after injury (see Chs 4,24,28-30 and 53). Adhesion molecules interact with each other and with nonadhesive cell-surface and/or cytoplasmic molecules, and, in the two... 

Fibroblasts, along with cells from adipose tissue, cardiac and skeletal muscle and the vascular endothelium, are derived from the mesenchyme while epithelial cells are obtained from the cervix, kidney tubes, bronchii, trachea etc. Neurones and glial cells are of neuroectodermal origin and blood cells arise from the haemopoietic system. 

As mentioned previously, myelination is carried out by highly specialized glial cells, oligodendrocytes in the CNS and Schwann cells in the PNS. These cells differentiate from precursor cells of different origin during development the neural crest for Schwann cells, and neural tube for oligodendrocytes. Myelin characteristics differ morphologically in the CNS and in the PNS, and differ also inside the CNS. Thus... 

The neural crest is a transient structure that arises from the dorso-lateral aspect of the closing neural tube. The cells migrate along several discrete tissue pathways and give rise to the majority of cells of the PNS, both neuronal and glial, melanocytes and adrenal medullary cells. In the cephalic region, crest cells give rise to additional cell types, in-... 

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