A PowerPoint review of photomicrographs depicting the various histological features of muscle tissues : skeletal, cardiac, and smooth. By Timothy Ballard, UNC Wilmington. Licensed under a Creative Commons License: Attribution Non-Commercial-NoDerivs. From http://www.lifescitrc.org/resource.cfm?submissionID=8992

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2. SSkkeelleettaall mmuussccllee
Skeletal muscle – longitudinal section – H&E – 10x objective
individual muscle fibers
nucleus
Skeletal muscle fibers (individual cells) are long and cylindrical, with multiple
nuclei that are placed on the perimeter of the fibers.

3. SSkkeelleettaall mmuussccllee
Skeletal muscle – longitudinal section – H&E – 20x objective
multiple nuclei on the
periphery of the cell
connective tissue and
blood vessels
between muscle fibers
By moving the fine-focus adjustment gently up and down, you can see the
alternating light and dark bands that form the striations.

4. SSkkeelleettaall mmuussccllee
Skeletal muscle – longitudinal section – H&E – 40x objective
multiple nuclei on the
periphery of the cell
connective tissue and
blood vessels
between muscle fibers
individual muscle fiber
The striations, peripheral nuclei, and parallel fibers are the selling points that
this is skeletal muscle seen in longitudinal section.

5. SSkkeelleettaall mmuussccllee
Human esophagus (upper) – section – H&E – 10x objective
muscle fibers See the striations?
multiple nuclei on the
periphery of the cell
longitudinal skeletal
skeletal muscle fibers
in cross section
See the peripherally-placed
nuclei?
The upper esophagus of the human has skeletal muscle in both cross and
longitudinal section.

6. SSkkeelleettaall mmuussccllee
Skeletal muscle – cross section – H&E – 40x objective
skeletal muscle fibers
in cross section
Why can’t you see the striations in a cross-section of skeletal muscle?

7. CCaarrddiiaacc mmuussccllee
Cardiac muscle – section – H&E – 10x objective
Cardiac muscle cells run parallel to one
another, but unlike skeletal muscle cells, the
individual fibers branch to meet other cells,
forming a meshwork or network of cells.
Compare this section with skeletal muscle. Look at the lack of parallel
organization of the fibers compared to that of skeletal muscle.

8. CCaarrddiiaacc mmuussccllee
Cardiac muscle – section – H&E – 20x objective
In this view the branching nature of the cardiac muscle cells is more visible. In
addition, look at the nuclei. How many are there and where are they?

9. CCaarrddiiaacc mmuussccllee
Cardiac muscle – section – H&E – 40x objective
intercalated disc
striations
centrally-located nucleus
One distinguishes cardiac muscle from skeletal muscle by the branching fibers,
presence of intercalated discs, and centrally-placed single nuclei/cell.

10. CCaarrddiiaacc mmuussccllee
Cardiac muscle –section – silver – 20x objective
branching
nucleus
intercalated disc
This stain clearly shows the single central nucleus, branching fibers,
intercalated discs, and striations.

11. SSmmooootthh mmuussccllee
Smooth muscle – teased apart – H&E – 20x objective
The tapered nature of these cells allows them to be fitted
together into sheets of cells, perfect for forming the walls of
hollow organs. In addition, the lack of sarcomeres means
that the muscle sheets can stretch to accommodate the
increased pressure within the organs.
Individual cells are long, thin, and tapered on the ends. There is a single
nucleus per cell, usually at its longitudinal center. There are no striations.

12. SSmmooootthh mmuussccllee
Large intestine – longitudinal section – H&E – 10x objective
mucosa submucosa muscularis externa
inner
circular
outer
longitudinal
Circular smooth muscle cells cut longitudinally would look like
Longitudinal smooth muscle cells cut longitudinally would look like

13. SSmmooootthh mmuussccllee
Duodenum – cross section – H&E – 40x objective
inner circular
smooth muscle
Circular smooth muscle cells cut in cross section would look like

14. SSmmooootthh mmuussccllee
Large intestine – longitudinal section – H&E – 40x objective
collagen fibers
smooth muscle
Contrast the smooth muscle cells with the collagen fibers just above them.
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