Basal laminas model

Peripheral nerve block is created by injecting ethanol around the selected nerve. The effect of alcohol on nerve tissue has been examined in animal models and in postmortem specimens from patients who received neurolytic blocks (8,9). In general, alcohol causes destruction of nerve fibers, with subsequent Wallerian degeneration. The basal lamina around the Schwann cell usually remains intact. This leaves a tract available for axon regeneration without the formation of a neuroma. If the cell bodies are completely destroyed, regeneration will not occur. Contact of alcohol with unintended nerve roots underlies many of the more serious complications. Involvement of anterior rootlets sufficient to interrupt motor nerve function will result in muscle weakness or paralysis. Interruption of... 

FIGURE 6-13 Major components of the basal lamina. Schematic model of basal lamina showing the organization of the major protein components. Type IV collagen and laminin each form two-dimensional networks, which are cross-linked by entactin and perlecan molecules. [Adapted from B. Alberts et al., 1994, Molecular Biology of the Cell, 3d ed., Garland, p. 991.1... 

A FIGURE 6-16 Laminin, a heterotrimeric multiadhesive matrix protein found in all basal laminae, (a) Schematic model showing the general shape, location of globular domains, and coiled-coil region in which laminin s three chains are covalently linked by several disulfide bonds. Different regions of laminin bind to cell-surface receptors and various matrix components. 

A) Stages of muscle development from mononuclear myoblast to the mature innervated myofiber. Nuclei, which are still centrally located in myotubes, move to the periphery in the mature fiber as a result of the synthesis of contractile elements in the sarcoplasm. Mature fibers contract and exhibit cross-striations. Only mononuclear myoblasts still have the capacity to divide and proliferate. Some of them do not fuse and become entrapped as mononuclear satellite cells under the basal lamina of the mature fiber. (B) Reproduction of this process in the experimental model of the in vitro innervated human muscle axons are labeled by arrows and functionally innervated myotubes by arrowheads. Cross-striations could be seen in the innervated myotubes at higher magnification (insert). 

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