SSB Histology Lab IIMuscle and Peripheral Nervous SystemSSB Week 2

►►► NOTE: Slide numbers may differ from box to box. If you don't have the slide listed, ask your colleagues.

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INTRODUCTORY COMMENT on MUSCLE.
The structure of striated, skeletal muscle is best studied by electron microscopy (i.e., through text-book pictures).
In Histology Lab, you should learn to recognize skeletal muscle -- which means distinguishing it from other fibrous, eosinophilic structures such as collagen and smooth muscle.

Slide 14, Striated Muscle.

(Note: This specimen displays isolated muscle samples, stained to accentuate the striations. Be sure to appreciate how plane-of-section affects the appearance of muscle fibers.)

(EASY) In the longitudinal section, observe striations. In the cross section, observe fiber diameter and myofibrillar structure. Note position of nuclei.

Slide 10, Fibrocartilage.

(Note: This specimen includes tissues of the pubic symphysis, with bone and cartilage as well as muscle.

(EASY) Find the skeletal muscle.

Slide 15, Muscle, 3 types.

(EASY) Compare and contrast smooth muscle, cardiac muscle, skeletal muscle. Questions: Can you see individual cells? Can you really tell where the nuclei are located?

Slide 17, Motor Nerve Endings.

(Note: This is a "just-for-fun" preparation. The specimen is a teased wholemount, not a section. A small bit of muscle, at a site of innervation, was dissected free and placed on the slide.)

(HARD?) Find some neuromuscular junctions. Hint: Don't just look randomly -- sweep across the specimen at low power and try to find black-stained nerve fibers. Then follow these to their destination.

Slides 29,30, Tongue

(EASY) Find the skeletal muscle (most of the bulk of the specimen). Note fibers with different orientations (i.e., different planes of section).

(HARDER) Make sure you can distinguish muscle from connective tissue.

(EASY?) Deep in the tongue, this specimen may also include prominent nerves.

Slide 46, Anal Canal.

(HARD?) This specimen may include both smooth and striated muscle. Determine what is present.

Slide 34, Esophagus.

(EASY) Find smooth muscle.

(HARD?) This specimen may or may not include a few striated muscle fibers. (The upper esophagus has striated muscle, the lower esophagus does not.)

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PERIPHERAL NERVOUS TISSUE.
We really don't have any elegant preparations that show special features of the peripheral nervous system. But there are a few structures which may be interesting to find.

Slide 55, artery, vein, nerve

(EASY) Find the nerve(s).

(EASY) Determine whether striated muscle is present.

(HARD?) IF striated muscle is present, look for a muscle spindle (spindles are present on some but not all specimens). Question: What makes muscle spindles recognizable?

Slide 2, 3, 4,Skin

(EASY?) Find a nerve. Hint: Look deep. Question: Do the axons in this nerve belong to sensory or motor nerve cells? Explain why.

(HARD) Find a Meissner's corpuscle. Hint: Don't bother looking unless the specimen on your slide shows thick skin. Questions: How you recognize thick skin? Where should you look for Meissner's corpuscles?

(EASY or IMPOSSIBLE) Find a Pacinian corpuscle. If one of these structures is present, it will be obvious (up to a millimeter in diameter, looking like an onion cut in half). But most of our slides do not include any.

Slide 17, Sensory Nerve Endings.

(Note: This is a "just-for-fun" preparation. The specimen is a teased wholemount, not a section. A small bit of muscle and tendon, at a site of innervation, was dissected free and placed on the slide.)

(HARD?) Find some sensory endings on the tendon. Hint: Don't just look randomly -- sweep across the specimen at low power and try to find black-stained nerve fibers. Then follow these to their destination. Question: How can you tell these are not motor endings?