Histo On Histo On Your NervesYour Nerves
SSN HistologySSN Histology
October 26th, 2004October 26th, 2004
Missy Walker, [email protected] Walker, [email protected]
So Young Kim, [email protected] Young Kim, [email protected]
Node of Ranvier
Perikaryon
Myelin-Producing Cell
So what’s in a nerve? So what’s in a nerve?
Axon Hillock
Dendrite
Axon Terminal
Axon
Nucleus of myelin-producing cells
Nervous System ClassificationsNervous System Classifications
Nervous System
CNS PNS
Spinal Cord Cerebellum Cerebral Cx ANS Somatic Enteric (Ganglia) (Peripheral Nerve)
Peripheral Nervous System (PNS)Peripheral Nervous System (PNS) Nervous tissue outside of the brain and spinal cordNervous tissue outside of the brain and spinal cord
Somatic Nervous System
• Innervates skeletal muscle
• For conscious movement
• Cell bodies in CNS
Autonomic Nervous System
• Innervates smooth muscle and glands
• For organ function and regulation
• Cell bodies in CNS and PNS
Sympathetic & Parasympathetic
ANS - GangliaANS - Ganglia
Sympathetic GANGLIA in thorax contain:
• neuronal cell bodies
• satellite cells (support cells of the neuron)
Synapses occur
• Presynaptic fibers myelinated
• Postsynaptic fibers unmyelinated
Enteric NS - GangliaEnteric NS - Ganglia
Myenteric plexus in ENS
• Within Smooth Muscle of Gut
• NO Collagen (as in CNS)
• Glial cells (no Schwann cells)
• Nuclei are euchromatic
• Gut has “mind of its own”
Cross section of nerveCross section of nerve
Organization by
Connective Tissues
• Endoneurium collagen fibers associated with individual neurons -Schwann cells within
• Perineurium layer(s) of connective tissue cells, create fascicles
• Epineurium dense cnxtive tissue binding fascicles into a bundle
Periph nerve Periph nerve - longitudinal section- longitudinal section
• Endoneurium• Perineurium• Epineurium
Peripheral Nerve – High Power (Cajal)Peripheral Nerve – High Power (Cajal)
• Nodes of Ranvier• Neurilemma
(cytoplasm of Schwann cells)
• What’s the black?
Peripheral Nerve – High Power (H&E)Peripheral Nerve – High Power (H&E)
What’s the purple? What’s the white?
Key Points for PNSKey Points for PNS• Ganglia
– Contain cell bodies for motor ANS
– Satellite cells are the supporting cell bodies (not glial, Schwann, or others of CNS)
• Peripheral Nerves
– Schwann cells make mylin sheath
– Node of Ranvier / saltatory conduction / Na channels
– Endoneurium around neurons, which form fascicles
– Perineurium around fascicles, which form bundles
– Epineurium around bundles