When one plate is composed of oceanic lithosphere and the other is composed of continental lithosphere, the denser oceanic plate is subducted, often forming an orogenic belt and associated mountain range. This type of convergent boundary is similar to the Andes or the Cascade Range in North America.hen one plate is composed of oceanic lithosphere and the other is composed of continental lithosphere, the denser oceanic plate is subducted, often forming an orogenic belt and associated mountain range. This type of convergent boundary is similar to the Andes or the Cascade Range in North America.
Myelinating Schwann cells wrap around axons of motor and sensory neurons to form the myelin sheath. The Schwann cell promoter is present in the downstream region of the human dystrophin gene that gives shortened transcript that are again synthesized in a tissue specific manner.
The myelin sheath is a greatly extended and modified plasma membrane wrapped around the nerve axon in a spiral fashion [ 1 ]. The myelin membranes originate from and are a part of the Schwann cells in the peripheral nervous system (PNS) and the oligodendroglial cells in the central nervous system (CNS) (see Chap. 1).Each myelin-generating cell furnishes myelin for only one segment of any given axon.wo adjacent segments of myelin on one axon are separated by a node of Ranvier. In this region, the axon is not covered by myelin. At the paranodal region and the Schmidt-Lantermann clefts, the cytoplasmic surfaces of myelin are not compacted and Schwann or glial cell cytoplasm is included within the sheath.