5.nervous Tissue

Nervous tissue consists of two types of cells: neuron and neuroglia. Nervous tissue forms the nervous system: central nervous system(CNS) and peripheral nervous system(PNS). The neuron is the structureal and functional unit of the nervous system. A neuron is composed of three parts: soma, dendrite and axon.

According to the prominence number of the neuron the neuron can be divided into three typers: psudounipolar neuron, bipolar neuron and multipolar neuron.

Specimen NO. 17.

neuron

satellite cell

Fig. 1. Section of spinal ganglion, showing psudounipolar neurons. HE stain. High magnification.

Specimen NO.14. white matter Anterior horn

Anterior horn Gray matter

posterior horn

posterior horn Central canal

Fig. 2. Cross section of spinal cord. HE stain Try to fine multipolar neuron in anterior horn.

Specimen NO.14. Soma of neuron nucleu s

Nissl body

axon

neurogliacyte

Fig. 3. Multipolar neuron of spinal cord. HE stain. 3.3×40

Specimen NO.14.

neurons neuron

axon

Nissl body

axon

Fig. 4. Multipolar neuron of spinal cord . HE stain. High magnification.

Specimen NO.15A

pyramidal cell

Fig. 5. Section of cerebral cortex, showing multipolar neuron — pyramidal cell. The body of pyramidal cell is triangle. There is an

Specimen NO.15A

①

②

Fig. 6. Section of cerebral cortex, showing ①Astrocyte, ②Small blood vessels. Silver Stain. High magnification.

Specimen NO.16A

cell body of Purkinje cell

dendrites

axon

Fig. 7. Section of cerebellum, showing mulipolar neuron — Purkinje cells Silver stain. High magnification.

A nerve fiber is composed of an axon and surrounding neuroglial cells. There are two types of nerve fibers: myelinated or unmyelinated.

Specimen NO. 19

neurolemma myelin sheath

axon

Node of Ranvier

Fig. 8. Longitudinal section of sciatic nerve showing myelinated nerve fibres HE stain . High magnification

Specimen NO. 19 myelin sheath

axon

neurolemm a

Fig.9. Cross section of sciatic nerve, showing myelinated nerve fibres. HE stain . High magnification.

Specimen NO.18

unmyelinated nerve fibres

Soma of neuron

Fig. 10. Section of sympathetic ganglion , showing unmyelinated nerve fibres. HE stain . Low magnification.

Nerve endings are the terminal structures of peripheral nerve fibers. They can be classified into sensory nerve ending and motor ending according to their functions.

Fig. 11. Free nerve endings in epidermis

Specimen NO.32

epidermis

tactile corpuscle

dermis

Fig. 12. Section of finger skin, showing tactile corpuscle. HE stain. 3.3×40

Specimen NO.32

Lamellar corpuscle

Fig. 13. Section of finger skin,showing lamellar corpuscle. HE stain . 3.3×40

Fig. 14 Muscle spindle

Specimen NO.21

Nerve ending

Skeleton muscle

Fig. 15. Motor end plates

Fig.17. Synapse is specialized junction between neuron and neuron or between neuron and effector cell.

Fig. 16. Neuroglia cells are supporting cells within the nervous system.

QUESTIONS 1. What components does the nervou tissue consis of? 2. How many components comprise the neuron? 3.What structure is Nissl body under the electron microscope? 4. what differences are there between nerve fiber and neurofibril? 5. Describe the microstructural features of peripheral myelinated nerve fiber. 6.What is synapse?