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Slide 1 Spinal Cord
In the spinal cord, the gray matter is found in the center (the butterfly shape) and the white matter surrounds it. The opposite arrangement is found in the cortex of the brain. Notice the dorsal root (blue arrow) and the surrounding dura mater (green arrow). |
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Slide 2 Central Canal
Within the spinal cord is the central canal that contains cerebrospinal fluid (CSF). Note the ependymal cells (simple cuboidal with cilia) than line the lumen.
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Slide 3 White Matter
The white matter of the spinal cord consists of myelinated fibers. Notice the numerous axons surrounded by clear space where the myelin was prior to tissue processing.
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Slide 4 Gray Matter
Gray matter within the spinal cord contains many nuclei such as this multipolar motor neuron. Notice the nucleolus (green arrow) within the nucleus (red arrow) and what appears to be an axon or dendrite (blue arrow).
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Slide 5 Gray Matter
Here again is a multi-polar cell (thionin stain). The smaller nuclei are glia (oligodendrocytes and microglia).
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Slide 6 Dorsal Root Ganglion (DRG)
Compare the large soma (perikarya) of the ganglion cells with the smaller myelinated nerves cut in cross section in the upper right. The DRG houses the nuclei of the peripheral sensory nerves, although there are no synapses in the DRG.
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Slide 7 Dorsal Root Ganglion
A higher magnification view shows the surrounding satellite cells (red arrows), the glia of the DRG.
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Slide 8 Cerebellum
H&E Slide. At low power, the cerebellum in distinguished by its three visible layers. The inner layer (blue arrow) is white matter on the inside compared to its "outer" spinal cord position. The outer layers are gray matter: granular layer (red arrow), molecular layer (green arrow), and Purkinje cell layer between those two layers.
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Slide 9 Cerebellum
The thionin stain shows the same layers as observed in slide 8. The short, dark lines are an artifact of fixation.
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Slide 10 Cerebellum
A closer look reveals that the gray matter of the cerebellum has three layers: granular layer (top arrow), monolayer of Purkinje cells (middle arrow), and the molecular layer (bottom arrow). The Purkinje cells send axons to other parts of the CNS.
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Slide 11 Cerebrum
The cerebrum also has its white matter (blue arrow) within its gray matter (red arrow). Notice the smooth homogenous layer 1 of the cortex (green arrow).
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Slide 12 Cerebrum
The cerebrum contains multipolar cells similar to those in the spinal cord. These are known as pyramidal cells.
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Slide 13 Cerebrum
If this neuron was America, the pale staining axon hillock would be Florida. Notice that the "brain center" of the cell (the nucleus with nucleolus) is located at the Kansas University Medical Center. Fitting, isn't it?
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Slide 14 Cerebrum
Arrows point to processes of the two multipolar cells. The larger, lightly-stained process (green arrow) is probably an axon and the smaller one (blue arrow) appears to be a dendrite.
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Slide 15 Astrocytes
Astrocytes are star-shaped glial cells of the CNS that have long processes. Many of these processes extend to blood vessels where they expand and cover much of the external wall. The expanded endings of the astrocyte processes are known as end-feet. While the blood-brain-barrier is formed by tight junctions between endothelial cells, the end-feet function to induce and maintain the blood-brain barrier. In pathology following stroke the relationship of end-feet to the endothelial cells is altered leading to disruption of the blood-brain barrier and subsequent leakage.
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Slide 17 Peripheral Nerve
Another look shows the same characteristics of the longitudinal peripheral nerve. The washed-out appearance and nodes of Ranvier distinguish it from smooth muscle, connective tissue, cartilage, etc.
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Slide 18 Node of Ranvier
A closer look shows a node of Ranvier (red arrow). These "breaks" in myelination allow for saltatory conduction. Use the RBCs as a size scale.
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Slide 19 Node of Ranvier
Another node of Ranvier more clearly shows the dark axon as it continues through the node. Notice again the washed out appearance of the nerve.
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Slide 20 Peripheral Nerve
In cross section, the dark axons are clearly seen within the myelin sheath (red arrow). Notice also the smaller B fibers (blue arrow). They too are myelinated.
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Slide 21 Pacinian Corpuscle
The Pacinian corpuscles are large "onion-like" encapsulated pressure receptors. The surrounding concentric lamellae respond to distortion and generate an action potential in the unmyelinated fiber in the core.
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