Name Date Hour. Nerve Histology Microscope Lab

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1 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 ) Type of neuron Number and type of processes Drawing Make up which branch(es) of nervous system Example Multipolar Bipolar Unipolar

Explain the relationship between the myelin sheath and nodes of Ranvier. 4. Complete the following chart using table 11.

2 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).

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.

3 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?

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.

4 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.

Purkinje cells, These large neurons are found in the cerebellum of the brain which controls many motor movements including coordination.

5 Cerebellar cortex Cerebral cortex Motor nerve Purkinje cells pyramidal cells 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 Cerebral cortex Motor nerve Purkinje cells pyramidal cells cells Classification: Classification: Classification:

Hypothesize what shape each of the above neurons would be (unipolar, bipolar or multipolar) * note we

Nervous Tissue Dr. Archana Rani Associate Professor Department of Anatomy KGMU UP, Lucknow

13.01.2015 Nervous Tissue Dr. Archana Rani Associate Professor Department of Anatomy KGMU UP, Lucknow Introduction Property of irritability and conductivity Respond to various types of stimuli Distributed