Nervous Tissue

【 Objectives 】 1. To identify and describe: A.The microscopic structure of the neuron— including cell body, axon and dendrites B. Differentiate a myelinated nerve fibers from an unmyelinated nerve fibers 2. To understand and describe A. The structure of a synapse B. The structure of sensory nerve termination (free nerve termination, tactile corpuscle, lamellar corpuscle and muscle spindle) or motor nerve termination (neuromusclar junction). C. General histological features of central nervous system, i.e. spinal cord, cerebellum, and cerebrum.

What is the principal elements of the NS? nervous tissue (NT) What does the nervous tissue consist of ? nerve cells (neurons) neuroglial cells (glial cell) What is feature of the nerve cells ? (soma, perikaryon) cell body processes dendrites axon plasma membrane cytoplasm: nucleus: Nissl body neurofibrils and neurofibrils ?? large, spherical, pale-staining; a prominent nucleolus distinguish? Axon hillock

Where do cell bodies of the neurons distribute? Where do processes of the neurons distribute? gray matter, cortex, nuclei white matter and the whole body Gray matter White matter

Observation: No1 central canalwhite matter Gray matter butterfly-like shape or H-like shape neuronal cell bodies,dendrites and the initial unmyelinated portions of axons and glial cells anterior horn posterior horn intermediate zone myelinated axons, oligodendrocytes Focus on neuron Neuron Glial cells

How many types of the nerve fibers? What are nerve fibers? Nerve fibers formed by the axon which be wraped by Schwann cells or oligodendrocytes CNS PNS myelinated NF unmyelinated NF

axon myelin sheath node of Ranvier What is the myelin sheath? How does the myelin sheath be formed? How does the impulse be propagated in the myelinated and unmyelinated fibers? How to distinguish the myelinated and unmyelinated fibers in the slides What is the function of the myelin sheath? i nternode

Observation: No31 sciatic nerve transverse section longitudinal section perineurium epineurium nerve nerve fibers are grouped in bundle Relationship between the nerve fibers and nerve

endoneurium axon myelin sheath node of Ranvier transverse section longitudinal section neurilemma

Unmyelinated nerve H & E Observation: No.41 transverse section of the nerve

Demonstration slide neurons （ Nissl staining ）

Neurofibril （ silver staining ）

Myelinated fibers （ osmic acid staining ）

sensory nerve ending A. free never ending B. encapsulated nerve ending a. tactile corpuscle; b. lamellar corpuscle c. muscle spindle

Meissner’s corpuscle (tactile corpuscles)Be involved the reception of light touch)

Pacinian corpuscles (lamellated corpuscles) Be involved the reception of coarse touch, deep or heavy pressure,vibration and tension

muscle spindle Detect changes in the length (distension) of extrafusal muscle fibers and relay this information to the spinal cord

Motor nerve terminations somatic motor nerve terminations visceral motor nerve terminations

Synapse （ silver staining ） in the LM Definition of the synapse; the structure of the synapse

Cerebrum A: molecular layer B: external granular layer C: external pyramidal layer D: internal granular layer E: internal pyramidal layer F: multiform layer Cerebral cortex (gray matter) White matter

Cerebellum A: molecular layer, B: Purkinje cell layer C: granular layer gray matter White matter

Myenteric nerve plexus

Oligodendrocytes

NT nerve cells (neurons) neuroglial cells (glial cell) (Supporting cells) Soma cell body dendrites: axon: processes plasma membrane: cytoplasm nucleus: excitable Nissl body neurofibrils LM: basophilic granular EM: rER, ribsom LM: brownish black filaments EM: neuofilaments and microtubule large, spherical, pale-staining; a prominent nucleolus. one or more /neuron; usually short and thick, and branched; dentritic spines on surfaces ; one axon each neuron; long and thin, does not branch profusely; derived from axon hillock; devoid of Nissl bodies; axon terminals (buttons) contain vesicles with neurotransmitters in them CNS: PNS: astrocytes, oligodendrocytes, microglia, ependymal cells Schwann cells, capsular cells (satellite cells)

NT nerve cells (neurons) neuroglial cells (glial cell) (Supporting cells) Soma cell body dendrites: axons: processes plasma membrane: cytoplasm nucleus: excitable Nissl body neurofibrils LM: basophilic granular EM: rER, ribsom LM: brownish black filaments EM: Neuofilaments and microtubule large, spherical, pale-staining; a prominent nucleolus. One or more /neuron; Usually short and thick, and branched; Dentritic spines on surfaces ; CNS: PNS: astrocytes, oligodendrocytes, microglia, ependymal cells Schwann cells, capsular cells (satellite cells) oligodendrocytes, Schwann cells surrounding nerve fiber myelinated NF unmyelinated NF nerve endings sensory (receptors) motor (effectors) free nerve endings tactile corpuscles Lamellated corpuscles muscular spindles somatic (motor end plate) visceral

Homework Draw the picture of the neuron.

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