Page 82 - Headlines Histology2024_Neat

NERVOUS TISSUE

• The nervous tissue functions as a communication network to receive stimuli
from both internal and external environment (exteroception) and subsequent
transmission of signals or information (interoception) throughout the body or
effector organs (muscles or glands).

• It is made up of nerve cells (neurons) and different types of supporting cells
collectively known as neuroglia.

Neuron

• It is the structural and functional unit of the nervous tissue that is
specialized in excitability and conductivity.

• Each neuron is composed of cell body (perikaryon) and cell processes.
• They are located in the gray matter of the central nervous system, eye (rods

and cones), ears (organ of Corti), olfactory mucosa, and ganglia.

Cell body (perikaryon)

• It includes the nucleus and its surrounding cytoplasm.
Nucleus

• The nucleus is large, spherical or ovoid and usually centrally located within
the perikaryon, but in autonomic neurons it has an eccentric position.

• The chromatin is completely dispersed and the nucleolus is prominent
(owl’s eye). With EM, a small amount of peripheral chromatin can be seen
on the inner aspects of nuclear envelop.

• The female sex chromatin (Barr body) is usually evident either close to the
nucleolus (cat) or the nuclear envelope (human being).

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