Lab 9 Histology and Gross Anatomy of the

Lab 9 Histology and Gross Anatomy of the Nervous System

Lab 9 Activities 1. Identify neuron, pyramidal cell, Purkinje cell, and peripheral nerve slides 2. Identify boldfaced structures on brain models 3. Identify specified parts in lab manual on sheep brain dissection 4. Identify cranial nerves (by name + number I - XII)

Parts of a Neuron n Soma Dendrites Axon

Cell Body (Soma) n n n Contains the usual cellular organelles Primary site of synthesis & metabolism Cell membrane contains receptors to respond to stimuli Cell membrane transmits graded potentials Most cell bodies are located within the CNS n n clusters of neuron cell bodies in the CNS are called nuclei clusters of neuron cell bodies in the PNS are called ganglia

Dendrites n n n Short, tapering, highly branched processes Not myelinated Contain some cell organelles Cell membrane contains receptors to respond to stimuli Transmit graded potentials towards the soma

Axons (nerve fiber) n n n Originate at a cone-shaped region – the axon hillock A single process that transmits action potentials away from the soma May be long (1 meter) or short (1 mm) May branch (=collaterals) Collaterals end at n n axonal terminals synapse with neurons or effector cells (muscles or glands)

The Myelin Sheath n Lipid-rich, covering of axons n n n Oligodendrocytes in CNS Neurilemmocytes in PNS Dendrites are never myelinated Protects & electrically insulates Increases speed of nerve impulses n 10 -150 x faster than unmyelinated fibers

Neurons STRUCTURAL CLASSIFICATIONS

Multipolar Neuron (slide #24) Many processes originate from soma

Bipolar Neuron Two processes originate from soma

Unipolar Neuron n A single process originates from soma

Neurons SPECIFIC TYPES

Pyramidal Cells (slide #29)

Pyramidal Cells

Purkinje Cells (slide #30)

Purkinje Cells of Cerebellum

Purkinje Cells

Purkinje Cells n cytoskeleton stain

Peripheral Nerve • Connective tissue elements: • Epineurium (wraps nerve) • Perineurium (wraps fascicle) • Endoneurium (wraps axon & myelin sheath)

Nerve, cross-section (slide #28) Epineurium Perineurium Endoneurium

Nerve, cross section, Fascicles Epineurium Perineurium Endoneurium

Nerve, cross section, Myelinated Fibers

Myelinated Axons, cross-section

Nerve, Long Section, 40 X (slide # 28)

Nerve, long section, 100 X

Neurofibrilar Node Nerve, 400 X

Neurofibrilar Node, 1000 X

Sheep Brain Dissection Dura mater partially removed

Sheep Brain Dissection and pia mater

Sheep Brain Dissection

Sheep Brain Dissection Note: pituitary removed

Sheep Brain Dissection

Sheep Brain in Cross Section

Key to Sheep Brain in Cross Section n n n n 1. 2. 3. 4. 5. 6. 7. 8. Gray Matter White Matter Corpus Callosum Lateral Ventricle Caudate Nucleus Septum Pellucidum Fornix Optic Chiasm n n n n 9. Third Ventricle 10. Thalamus 11. Corona Radiata 12. Hippocampus 13. Cerebral Aqueduct 14. Pituitary Gland 15. Pineal Gland

Human Cranial Nerves

End of Lab 9 Presentation