Lab 8 Peripheral Nervous System: 1) Index 2) Introduction 3) Things To identify 4) Nerve and Nerve Fibers 5) Nerve & Nerve Fibers II 6) Nerve & Nerve Fibers III 7) Dorsal Root Ganglion 8) Sympathetic Ganglion 9) Parasympathetic Ganglion 10)Practical

 

Nerve & Nerve Fibers III

 

3. #56 - Medullated nerve, c.s. and l.s., h-e

 

Attempt to locate interruptions in the myelin sheath which are called nodes of Ranvier. By carefully searching, you should find several examples of these structures. You may also detect repeated diagonal marks in the myelin sheath called Schmidt-Lanterman incisures, which are areas where the cytoplasm of the Schwann cell was trapped in the myelin sheath during the "wrapping" process. Note that the larger the axon, the larger the internodal length of myelin (and thus the larger the axon, the faster the impulse).

References: Ross, p. 265 DiFiore, p. 93, Fig. 7-6Gartner, p. 143, Fig. 1 - 2

 

This is a slide of Medulated Nerve. In this slide the Red arrows are pointing out the Nodes Of Randvier, which is the gap between two schwann cells.. As mentioned earlier, this is the site of saltutory conduction, that allows for the nerves to conduct action potentials quickly down the axon. The two bulges on either side of the node are the ends of the Schwann Cells.

Red arrow - Nodes of Ranvier

 

 

 

This is another shot of medulated nerve. The Red arrow is showing another example of a Node of Ranvier. The blue arrows are pointing to a defect in the myelin sheaths of the axons called Schmidt Lantermann Incisures. Can you tell the difference between the Schmidt-Lanterman incisures and the Nodes of Ranvier. The nodes have more curved end on either side of it, while the incisure is more of a sharp line. These are the main things to recongize in meduallated nerve.

Blue arrow - Schmidt Lantermann incisure

Red arrow - Nodes of Ranvier

Medulated Nerve (Nodes of Ranvier)

Medulated Nerve (Schmidt Lanterman Incisure)