Muscle Tissue

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Stephen E. Fish, Ph.D. Mitchell L. Berk,
Ph.D. Marshall University J. C. E. School of
Medicine
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Note to instructors I use these PowerPoint
slides in histology lectures that I give to first
year medical students. Copy the slides, or just
the images into your own teaching media. We all
know that teaching science often requires
compromises and simplification for specific
student populations, or the requirements of a
specific course. Please feel free to offer
suggestions for improvements, corrections, or
additional illustrations. I would be pleased to
hear from anyone who finds my work useful, and am
always willing to make it better. Also, the
images have been compressed to screen resolution
to keep PowerPoint file size down, and I can
provide them at any resolution. Contact me about
the illustrations and Mitchell L. Berk about the
photomicrographs. Stephen E. Fish,
Ph.D. Fish_at_Marshall.edu Berk_at_Marshall.edu
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Cardiac Muscle
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Cardiac muscle

• Stains eosinophilic in HE
• Rounded nuclei (sometimes 2) inside the cells
• Cells joined by intercalated disks to make a
  fiber
• Cross striations from sarcomeres longitudinal
  stripes from loose myofibrils

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Longitudinal
Cross section
Longitudinal
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Endomysium
Perimysium
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Slide Muscle 7, cardiac muscle, longitudinal
section, 40X
centrally located nucleus in fiber
Branching of fibers
Fibers branch
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Branching fiber
Intercalated disc
Cross striations (sarcomeres) are just visible,
longitudinal stripes (loose myofibrils) are more
apparent
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The cardiac sarcomere (T-tubules at Z lines, no
triads, sarcoplasmic reticulum is an anastomosing
network
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Intercallated disk detailNote zigzag is in
multiples of a sarcomere
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Heart layers
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Connectivity organizes spread of contraction in
the interconnected fibers
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Cardiac muscle
Purkinje fiber
Endocardium
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Purkinje fibers (note reduced disorganized
myofibrils)
binucleate cell
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Smooth muscle
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• Eosinophilic cytoplasm minimal endomysium
• Speckled hot dog central nucleus looks small
  circular in cross section
• Fiber is a single cell with a single nucleus

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GI smooth muscle, low power
Epimysium
Smooth muscle
Cross section
Longitudinal
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Smooth muscle in the GI tract (muscularis externa)
Longitudinal
Cross section
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Smooth muscle
Longitudinal
Cross section
Perimysium
Endomysium not visible
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Smooth muscle contractile mechanisms
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Sherman says
Muscle is an important component of dog food