Download Nerve Histology Microscope Lab PRE-LAB

Name _________________________________ Date ______________ Hour ________
Nerve Histology Microscope Lab
PRE-LAB: Answer the following questions using your reading and class notes before
starting the microscope lab.
1. What is the difference between the functions of neurons and neuroglia?
2. Explain the role of Schwann cells in the formation of the myelin sheath.
3. Explain the relationship between the myelin sheath and nodes of Ranvier.
4. Complete the following chart using table 11.1 to show the differences between the
three structural differences in neurons: (green book p. 396-397)
Type of neuron
Multipolar
Bipolar
Unipolar
Number and
type of
processes
Drawing
Make up which
branch(es) of
nervous system
Example
PART 1: Identifying Parts of a Neuron (Slide: Mammal Peripheral Nerve c.s. &
l.s.)
A. In this slide, you will need to view the longitudinal section of the nerve which will be
the longer specimen on the top half of the slide. There will be many neurons sitting
in “rows” next to one another. These are bundles, which as a whole, make up a
nerve. You are looking at multiple axons surrounded by myelin sheaths. The places
where the sheaths merge are the nodes of Ranvier. Use your atlas on page 14 (plate
35) to help you identify the parts of the neuron.
1. Sketch the nerve in the space provided below using colors and shapes that match
what you see.
2. Label the following structures: nucleus of a Schwann cell, axon, myelin, and if
you can see one, a Node of Ranvier (some slides this will be difficult to find).
B. A nerve is a bundle of neuron fibers or processes wrapped in connective tissue
coverings that extends to and/or from the CNS to visceral organs and other structures
of the body. Like neurons, nerves are classified based on the direction they send
nervous impulses- including motor (efferent) nerves and sensory (afferent) nerves.
Move the slide to the crosss section and look at the outer edge. You will see a
transverse cut through a neuron with the axon in the center (pink) which will look like
a nucleus. The axon is surrounded by the myelin sheath (lighter pink or white in
color).
1. Draw a picture of the cross section using accurate shapes and colors.
2. Compare your slide to the picture in your atlas on pg. 14, plate 34. Label the
following structures: axons, myelin sheath
Questions for Part 1:
1. Using your observations of this slide, define a nerve.
2. The bundle of neurons are all surrounded by connective tissue. What function do
you think this connective tissue serves?
PART 2: Studying the Microscopic structure of selected neurons
(SLIDES: Cerebellar cortex- Purkinje cells; Cerebral cortex- Pyramidal
cells; and Motor nerve cells, smear, ox spinal cord)
Structurally, neurons are classified as multi-polar, bipolar and unipolar. They differ in
the lengths of their processes (dendrites and axons) and their proximity to the cell body.
Purkinje cells, These large neurons are found in the cerebellum of the brain which
controls many motor movements including coordination. Most Purkinje cells releases a
neurotransmitter that inhibits surrounding neural messages allowing them master control
over motor movements. The loss of or damage to Purkinje cells can give rise to certain
neurological diseases. During embryonic growth, Purkinje cells can be permanently
destroyed by exposure to alcohol thereby contributing to the development of fetal alcohol
syndrome. The loss of Purkinje cells has been observed in children with autism.
Pyramidal cells: These cells make up the cerebrum which is used for logical thinking
and problem solving. They usually contain many branches in their processes and make
connections with other neurons. Connections are created when learning occurs, so there
is a correlation between the number of branches in the axon and dendrites and a person’s
cognitive ability.
Motor nerve cells: These neurons innervate the muscle directly to create movement,
hence they are part of the peripheral nervous system.
1. Review the structural differences between the three types of neurons in your
notes.
2. Obtain the prepared slides listed above. As you observe them under the
microscope, note anatomical details and compare them to the pictures in your
reading notes.
a. Cerebellum Purkinje cells- In low power you will see a dark purple
“swirl” that surrounds lighter pink tissue. Position the pointer where these
two colors meet and focus in high power. Follow the border between
these two tissues until you view a cell body shaped like a tear drop.
b. Cerebral cortex pyramidal cells: These neurons are stained with silver
stain which will make the cells very dark against the surrounding tissue
allowing you to observe their shape.
c. Motor nerve cells: This slide is a jumble of many motor neurons.
3. Draw each of the slides below. Label the following structures on each drawing:
Cell body, nucleus, dendrite, axon.
Cerebellar cortex
Purkinje cells
Cerebral cortex
pyramidal cells
Motor nerve
cells
Think about the classifications we use based on structure. Hypothesize what shape
each of the above neurons would be (unipolar, bipolar or multipolar) * note we do
not see one of each in these slides!
Cerebellar cortex
Purkinje cells
Cerebral cortex
pyramidal cells
Motor nerve
cells
Classification:
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Classification:
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Classification:
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