Histology Guide

virtual microscopy laboratory

Chapter 4 - Muscle Tissue

Muscle tissue is composed of cells that maintain the contractile function of connective tissue. Three types of muscle tissue are recognized based on their structure, function, and location:

In all types of muscle, contraction is caused by the movement of myosin filaments along actin filaments.

The terms muscle fiber and muscle cell are synonymous.

Skeletal Muscle

Skeletal muscle fibers, also known as myofibers, are long, cylindrical cells that are quite large, often spanning the entire length of a muscle.

A sarcomere is the fundamental contractile unit of striated muscle fibers.

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Sarcomere
Longitudinal Section
TEM
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Sarcomere
Cross Section
TEM
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Sarcomere
SEM (deep etching)

Cardiac Muscle

Cardiac muscle cells has branching fibers, a single, centrally located nucleus, show the same striations as skeletal muscle, and are under involuntary control.

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Sarcomere / Intercalated Disc
SEM
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Sarcomere / Intercalated Disc
SEM
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Sarcomere / Intercalated Disc
TEM
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Cross-Section
TEM

Smooth Muscle

Smooth muscle cells are spindle-shaped (fusiform), have a single, centrally located nucleus, lack striations, and are under involuntary control.

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Relaxed and Contracted
SEM
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Longitudinal Section
TEM
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Cross-Section
TEM
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Cross-Section
TEM