Medical School Histology Basics Peripheral Nerve VIBS 243

Medical School Histology Basics Peripheral Nerve VIBS 243 lab Larry Johnson Texas A&M University

NERVOUS TISSUE Ref code # 18 FUNCTIONS: SPECIALIZED FOR THE TRANSMISSION, RECEPTION, AND INTEGRATION OF ELECTRICAL IMPULSES DISTINGUISHING FEATURES: NEURONS – VERY LARGE EXCITABLE CELLS WITH LONG PROCESSES CALLED AXONS AND DENDRITES. THE AXONS MAKE CONTACT WITH OTHER NEURONS OR MUSCLE CELLS AT A SPECIALIZATION CALLED A SYNAPSE WHERE THE IMPULSES ARE EITHER ELECTRICALLY OR CHEMICALLY TRANSMITTED TO OTHER NEURONS OR VARIOUS TARGET CELLS (e. g. , MUSCLE). OTHERS SECRETE HORMONES.

NERVE IS LIKE EPITHELIUM ORIGIN OF NERVE IS ECTODERM LIKE EPIDERMIS (EPITHELIUM) OF SKIN Ref code #2

Ref code # 5, 6

492 Peripheral ganglion monkey Myelinated axons Ref code #6

DEMO SLIDE BOX 76. Ganglia, dog. Nissl bodies = cytoplasm for coarse aggregates of basophilic substance = Rough Endoplasmic Reticulum and Polyribosomes Nucleus contains a large, prominent nucleolus and an abundant amount of euchromatin = Neurons are metabolically active cells Satellite cells Surrounding each cell body should be a variable number of nuclei of Satellite cells

492 Peripheral ganglion monkey Nissl substance 492 Ref code #6

440 Ganglion cell bodies in pancreas

29291 Bile ducts in monkey Ganglion cell body in cystic bile duct vein

DEMO SLIDE BOX 78. Dorsal root ganglion & nerve, cat. small ganglion and a cross-section of nerve

DEMO SLIDE BOX 78. Dorsal root ganglion & nerve, cat. small ganglion and a cross-section of nerve dark “dots” (these are the axons) surrounded by “white circles” (myelin sheath)

Remember Connective Tissue Layers of Skeletal Muscle Epimysium, Perimysium, and Endomysium Ref code #6

Organization of Peripheral Nerves Nerve fibers - axons invested by connective tissue Epineurium - surrounding entire nerve Perineurium - surrounding fascicles – constitutes the PNS blood barrier via tight junctions between fibroblasts Endoneurium - between individual nerve axons Ref code #6

Organization of Peripheral Nerves Ref code # 12

DEMO SLIDE BOX 78. Dorsal root ganglion & nerve, cat. small ganglion and a cross-section of nerve Epineurium surrounding entire nerve Perineurium surrounding fascicles – Endoneurium between individual nerve axons

Types of Nerves Ref code #7

HISTO 0280 Bipolar neurons bipolar neurons of the inner ear Slide HISTO 0280 at the left hand side of the cochlea on the bottom circle Ref code #7

152 Duodenum (small intestine) Nerve (Auerbach's plexus) circular and longitudinal smooth muscle layers Submucosal glands mucosa Gut lumen

152 Duodenum (small intestine) Auerbach's plexus, which can be found in between the circular and longitudinal smooth muscle layers Auerbach's plexus Nerve cell bodies

epithelium 32409 Smooth muscle cells (Auerbach's plexus) Nerve cell bodies Meissner’s plexus cell bodies

EM 10 c: postganglionic neuronal cell body in an Auerbach’s plexus; 22, 000 x 1. Nissl substance 2. Neurosecretory vesicles

SCHWANN CELLS MYELIN Ref code #6

NODE OF RANVIER

DEMO SLIDE BOX 78. Dorsal root ganglion & nerve, cat. small ganglion and a cross-section of nerve axons, myelin sheath, node of Ranvier 492 perineurium Schwann cell nucleus

Peripheral nerve, monkey nodes of Ranvier Ref code #6 193

440 Nerve in connective tissue of a salivary gland Perineurium

492 Nerve nodes of Ranvier

SCHWANN CELL STRUCTURE / FUNCTION Ref code # 6, 12

Ref code # 7, 12 MYELINATION and SCHWANN CELLS

109 Skin hand monkey nerve Fibroblasts nerve Endoneurium Perineurium Nerve

105 Nerves in tissues/organs Nerves 109 105 Perineurium

196 Human spermatic cord with vessels and nerve

Human spermatic cord UT 196 Ductus deferens Blood vessels Nerve Perineurium Nerve

Perineurium EM 10 d: Schwann cells and axons; 21, 000 x print 1. Microtubule 2. Myelinated coat around a myelinated axon 3. Schwann cell cytoplasm around an unmyelinated axon 4. Vesicle in axoplasm 5. Nucleus of a Schwann cell

NEURONAL STRUCTURE / FUNCTION Axonal transport Anterograde - toward terminal - kinesin Retrograde - toward cell body - dynein • Tetanus toxin • Neurotropic viruses (herpes and rabies) use path to get to cell body in CNS

Neuronal Structure / Function

Neuronal Structure/Function Use retrograde axonal transport to map brain

Ref code # 5, 6 Motor end plates in skeletal muscle One nerve innervates several muscle cells Slide HISTO 007 Histo 07 Skeletal muscle cells : Skeletal muscle motor end plates

Summary of the Physiological Events at the Synapse • Arrival of action potential at axon terminal • Opening Ca++ channels • Influx of Ca++ into axon terminal • Exocytosis of neurotransmitter • Diffusion of neurotransmitter across synaptic cleft • Binding of neurotransmitter to receptors on target cell • Opening of Na+ channels causing depolarization of target cell • Removal of neurotransmitter

EM 10 e: Nerve terminal on smooth muscle; 41, 000 x print 1. Synaptic cleft 2. Synaptic vesicles 3. Smooth muscle

136 monkey tongue Skeletal muscle fibers (cells) Muscle spindles Intrafusal muscle fibers inside the capsule

105 Fingertip, monkey - sweat glands and ducts among Pacinian corpuscles

Skin hand monkey 109 Eccrine sweat glands Adipocytes Hypodermis Pacinian corpuscles Papillary layer Dermal papillae Epidermal peg

Slide HIST 0 29: Thick Skin (ventral surface of finger) Meissner’s corpuscles in dermal papillae Epidermis Epidermal peg Dermal papillae Dermis Meissner’s corpuscle is a mechanoreceptor Epidermis nerve ending for sensitivity to light touch; you would find more on your fingers because they are more sensitive to touch than your elbow.

Histo 29 Meissner’s corpuscles Dermal papillae Slide HIST 0 29

Slide 426: Renal artery and vein with nerves Smooth muscle cells, peripheral nerve fibers(axons) and bundles of collagen fibers Fibroblasts

109 : Skin, hand, monkey Fibroblasts Peripheral nerve fibers (axons) Smooth muscle cells Bundles of collagen fibers Fibroblast

Slide 196: Spermatic cord Bundles of collagen fibers Peripheral nerve fibers White fat cells Nerve Smooth muscle cells

34460 Human spermatic cord with nerve toluidine blue Bundles of collagen fibers Endothelium Perineurium Peripheral nerve fibers Smooth muscle cells Nerve Fibroblasts

Many illustrations in these VIBS Histology You. Tube videos were modified from the following books and sources: Many thanks to original sources! 1. Alberts, et al. , 1989. Molecular Biology of the Cell. 2 nd Edition. Garland Publishing, Inc. New York. ISBN 0 -8240 -3695 -6. 2. Alberts, et al. , 1994. Molecular Biology of the Cell. 3 nd Edition. Garland Publishing, Inc. New York. ISBN 0 -8153 -1619 -4. 3. Bloom, W. and Fawcett, D. W. , 1968. A Textbook of Histology. 9 th Edition. W. B. Saunders Company. Philadelphia. Library of Congress #67 -17445. 4. Elias, H. et al. , 1978. Histology and Human Microanatomy. A Wiley Medical Publication. John Wiley & Sons, New York. ISBN 0 -47104929 -8. 5. Eroschenko, V. 2000. Di Fiore’s Atlas of Histology with Functional Correlations. 9 th Edition. Lippincott Williams & Wilkins. Philadelphia. ISBN 07817 -2676 -X. 6. Fawcett, D. W. , 1986. Bloom and Fawcett. A Textbook of Histology. 11 th Edition. W. B. Saunders Company. Philadelphia. ISBN 0 -72161729 -8. 7. Fawcett, D. W. , 1994. Bloom and Fawcett. A Textbook of Histology. 12 th Edition. Chapman and Hall. New York. ISBN 0 -412 -04691 -1. 8. Guyton, A. C. 1971. Textbook of Medical Physiology. 4 th Edition. W. B. Saunders Company. Philadelphia. Library of Congress # 74118589. 9. Ham, A. W. 1974. Histology. 7 th Edition. J. B. Lippincott Company. Philadelphia. ISBN 0 -397 -52062 -X. 10. Ham, A. W. and Cormack, D. H. 1979. Histology. 8 th Edition. J. B. Lippincott Co. Philadelphia. ISBN 0 -397 -52089 -1. 11. Junqueria, et al. , 1995. Basic Histology. 8 th Edition. Appleton and Lange. Norwalk, Connecticut. ISBN 08385 -0567 -8. 12. Junqueira, et al. , 1998. Basic Histology. 9 th Edition. Appleton and Lange. Stamford, Connecticut. ISBN 0 -8385 -0590 -2. 13. Knobil, E. et al. 1988. The Physiology of Reproduction. Volume 1. Raven Press. New York. ISBN 0 -88167 -281 -5. 14. Langley, et al. , 1974. Dynamic Anatomy and Physiology. 4 th Edition. Mc. Graw-Hill Book Company. New York. ISBN 0 -07 -036274 -2. 15. Mescher, A. L. , 2010. Junqueira’s Basic Histology Text and Atlas. 12 th Edition. Mc. Graw Hill Medical. New York. ISBN 978 -0 -07 -1604314. 16. Tuttle, W. W. and Schottelius, B. A. 1969. Textbook of Physiology. 16 th Edition. The C. V. Mosby Company. Saint Louis. Library of Congress # 7589848. 17. Varner, D. et al. 1991. Diseases and Management of Breeding Stallions. American Veterinary Publications. Goleta, California. ISBN 0939674 -33 -5. 18. Von Hagens, Gunther and A. Whalley, 2007. Body Worlds – The Anatomical Exhibition of Real Human Bodies. ISBN 978 -3 -937256 -04 -7 19. Weiss, L. 1983. Histology: Cell and Tissue Biology. 5 th Edition. Elsevier Biomedical. New York. ISBN 0 -444 -00716 -4. 20. Weiss, L. and Greep, R. 1977. Histology. 4 th Edition. Mc. Graw-Hill Book Company. New York. ISBN 0 -07 -069091 -X.

Questions on nerves Which is not a distinguishing feature of the nervous system a. Comprise the central and peripheral nervous system. b. Individual peripheral nerves are found in limited places in the body. c. Individual neurons and clusters of neurons (called ganglia) are found in most organs d. a and b e. a, b, and c Which embryonic origin – tissue type(s) match(s)? a. Ectoderm – nerve b. Endoderm – muscle c. Mesoderm – nerve d. a and b e. a, b, and c

Big Bend National Park, TX

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