MUSCLE HISTOLOGY LAB
Professor of Biology and Chemistry
University of Cincinnati Clermont College,
Batavia OH 45103
rvsd 10 November 1994, rvsd 12 Sept '95, 25 Nov. '96, 19 Sept 99, 4 Oct 01, 8 Nov 01
See Martini's, 6th, pp 320-327, Eroschenko's 9th , pp 75-83.
Muscle is a contractile tissue which generates tension through the molecular pull exerted on actin by myosin fibers in the sarcomere (review these terms in your text). There are three histological classes of muscle, each of which functions in a unique way. Evidence of repeating sarcomere units can be seen in the cross striations of striated and cardiac muscle. The dark "A bands" are arrays of myosin. The light "I bands" are the spaces in between where there is no myosin. Look closely at a longitudinal section of skeletal muscle to see these bands.
I. Smooth muscle cells are tapered at the ends and possess a single centrally located nucleus. Their sarcomeres are not arranged in an orderly repeating fashion, and therefore the cells lack visible striations. These cells are slow contracting, and are responsible for involuntary visceral contractions (peristalsis, uterine contractions, bladder contraction, "bristling" of skin hairs, vasoconstriction, etc).
II. Striated muscle consists of multinucleated fibers produced by the fusion of many individual cells to form a muscle "fiber". The nuclei and mitochondria are pushed to the outside of the fiber. It owes its striations to regular, repeated arrangement of sarcomeres. It is voluntary, rapid acting, and relatively easily fatigued. It is also known as skeletal muscle, and is responsible for movement of bones.
III. Cardiac muscle,
also termed "striated involuntary muscle," is found only in the
heart. Its cells usually contain a single centrally located
nucleus, display striations as in striated muscle, but, due to
branching interconnections, appear woven together under the
microscope. In contrast to striated muscle fibers, their nuclei
are centrally located in the fibers. The interconnections
between fibers, intercalations,
diagnostic of cardiac
muscle but visible only when
with iron-containing stains. It is capable of intrinsically initiated
Draw each slide at 400x:
|Click on image to
|Tissue and slide||Features to identify|
|(slide 16) Smooth Muscle.
VE: fig 5-2, p 77
(Draw three or four of
out individual smooth muscle cells. These are hard to see, so carefully follow microscope
protocol (focus first on the edge of the cover slip).
|nuclei located half
way between ends of the cells
smooth muscle fibers "spindle" shaped (tapered at each end)
|(slide 17) Striated
VE: fig 5-3, p 79 and 5-9, p 85
This specimen is from the tongue which is particularly good to show traits of skeletal muscle because it has fibers running at right angles to each other, allowing a longitudinal as well as a cross sections in a single view.
Here is a labeled 450x view of skeletal muscle .
binding muscle fascicles together (dark encircling
muscle fascicle bundle of muscle fibers: include them in both c. s. and l. s.
endomysium binds individual fibers into a muscle fascicle (lines between fibers)
muscle fiber formed from fused muscle cells, show in both c. s. and l. s.
nuclei of muscle fibers note that they are multiple and pushed to the edge of the fiber
capillaries in endomysium clearly defined round holes at junctions of fibers
A band dark band in the cross striations, corresponds to myosin fibers
I band light band, corresponds to space between ends of myosin
VE: fig 5-7 & 5-10, p 83 & 85
Two slides are
shown. The upper
two images are from cardiac muscle stained with
It shows centrally located nucleii, but not
intercalated discs, one of the diagnostic features for cardiac muscle.
Here is a
labeled image of cardiac muscle stained with H&E
|nucleus of cardiac fiber
is larger, and is located in central position in cardiac
interwoven fibers characteristic of cardiac muscle
perinuclear sarcoplasm space around the nucleus lacking banding, not seen in striated muscle
intercalated discs join adjacent cardiac fibers end to end, only visible in iron-stained specimens
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