| 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 |
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Nerve & Nerve Fibers |
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| 1. # 62 - Nerve, human, c. s. and l. s., H&E |
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See Gartner, p. 124-125 for orientation. These slides show longitudinal and cross sections through a peripheral nerve trunk which contains many nerve fibers or axons. Hematoxylin and eosin were used to stain this specimen and the axons, Schwann cells and connective tissue are all stained. Since the myelin has a high lipid content, this will not be stained and will have dissolved away during tissue preparation. The longitudinal streaks with a "bubbly" appearance seen throughout this section are myelinated nerve fibers. They have a zigzag or wavy appearance (this prevents breakage of the nerve fibers during muscular activity. It is difficult to distinguish between the more numerous nuclei of Schwann cells and the nuclei of the fibroblasts of the endoneurium, the delicate C.T. sheath of collagen and reticular fibers that covers the individual nerve fiber and its Schwann cell. (Fibroblast nuclei are more condensed and slender than those of Schwann cells, but it is usually difficult to conclusively identify these two cell types on a tissue section. Compare the morphology of a longitudinal section of a peripheral nerve with that of tendon and smooth muscle. Can you distinguish differences among these tissue? (Refer to Plate 5 and 6 of Upjohn's publication, Look Alikes in Histology). How would a peripheral nerve stained with hematoxylin and eosin appear in cross section? REFERENCES: Ross, p. 292, Fig. 1 - 4 Gartner, p. 142- 143, Fig. 1 - 3Wheater, p. 126 - 127 , Fig. 7.13 - 7.16 DiFiore, p. 93 - 95, Fig. 7-7 - 7-13 |
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This is a cross section of a peripheral nerve. THe blue arrow is pointing out the individual nerve fibers that look like an eye ball with a pupil in the middle. The red arrows are pointing to the outer dark border of the nerve fibers. This line coresponds to the Neurilemma, or Schwann-Cell Myelin Sheath. The black arrows are pointing to what would be the"pupil of the eye" in our analogy, which is the axon and the axoplasm, which is the cytoplasm of the axon. These are the main features of the Nerve Fiber that can be seen in a cross section. Blue Arrows - Nerve Fiber Red arrow - Neurilemma or Schwann Cell Sheath. Black arrow - Axons of Nerve fibers
This is a longitudinal section of a Peripheral Nerve. Nerve Fibers in a longitudinal section have a characteristic wavy look, which you can observe by following the white arrow and looking at the tissue at the curves. The blue arrows are pointing to nuclei located with in the nerve, that has two possible owners. One is the Schwan cells which are resposible for the myelin sheat or the fibroblasts synthesizing the collagen and reticular fibers. White arrow - Wavy Look of Nerve in Longitudinal Sect. Blue arrow - Nuclei of Fibroblast or Schwann Cells
This is a high power shot of Nerve in Longitudinal section. At this magnification you can see what is know as the Nodes of Ranvier, (blue arrow). These are the gaps in between two Schwann Cells on a nerve fiber where Saltutory Nerve Conduction takes place. The two swellings on either side of the line are the ends of the schwann cells. The Red arrow is pointing to either the nuclei of fibrobalst or schwann cell Red arrow - Nuclei of Fibroblast or Schwann Cell Blue arrow - Node of Ranvier |
Peripheral Nerve Bundle (cross section)
Nerve (logitudinal section)
Nerve (Nodes of Ranvier) |
