BIO 240 HISTOLOGY REVIEW
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BIO 240 HISTOLOGY REVIEW Nervous Tissue PowerPoint PPT Presentation


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BIO 240 HISTOLOGY REVIEW Nervous Tissue. Dr. Tim Ballard Department of Biology and Marine Biology. Orientation to the spinal cord. Spinal cord – cross section – silver – 4x objective. dorsal horns of gray matter. central canal. gray commissure. dorsal. ventral.

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BIO 240 HISTOLOGY REVIEW Nervous Tissue

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Bio 240 histology review nervous tissue

BIO 240 HISTOLOGY REVIEWNervous Tissue

Dr. Tim Ballard

Department of Biology and Marine Biology


Bio 240 histology review nervous tissue

Orientation to the spinal cord

Spinal cord – cross section – silver – 4x objective

dorsal horns of gray matter

central canal

gray commissure

dorsal

ventral

ventral horns of gray matter

Silver stains nerve cells and unmyelinated fibers brownish-black. The white matter is lightly stained because there is so much myelin around the fibers.


Bio 240 histology review nervous tissue

Ventral motor neurons

motor neurons

Spinal cord – cross section – silver – 10x objective

In the ventral horn there are very large motor neurons. The brown fibers you see leaving the ventral horn are axons from these neurons.


Bio 240 histology review nervous tissue

Ventral motor neurons

Spinal cord – cross section – silver – 40x objective

These much smaller cells are likely to be neuroglial cells.

neuronal cell body

neuronal cell body

dendrites

nucleus with a nucleolus

Think in three dimensions. Where would the dendritic zone or the axon be related to this two-dimensional section?


Bio 240 histology review nervous tissue

Ventral motor neurons

Spinal cord – cross section – silver – 40x objective

nucleus with a nucleolus

This could be an axon hillock. Compared to the other branches here, this has a larger diameter, so it could be giving rise to an axon.

Seeing Nissl substance and neurofibrils within cell bodies requires special stains. With careful fine-focusing, you may get a sense of these intracellular materials.

Look at all of the cross-hatching brown-black fibers between the cell bodies. This is the “neuropil,” all of the axons of the gray matter connecting cells.


Bio 240 histology review nervous tissue

Ventral motor neurons

Spinal cord – cross section – Nissl’s stain – 40x objective

ventral motor neuron

neuroglial cells

Look at the differences in size between neuronal cell bodies and neuroglia.


Bio 240 histology review nervous tissue

Cerebellar cortex

Cerebellum – section – silver – 4x objective

Purkinje cell layer

gray matter

white matter

Silver stains nerve cells and unmyelinated fibers brownish. The white matter is heavily stained due to the presence of myelinated fibers.


Bio 240 histology review nervous tissue

Cerebellar cortex

Cerebellum – section – silver – 10x objective

molecular cell layer

Purkinje cell layer

granular cell layer

Look at the differences in neuronal sizes between the three layers of neurons shown above.


Bio 240 histology review nervous tissue

Cerebellar cortex

Cerebellum – section – silver – 40x objective

molecular cell layer

granular cell layer

Purkinje cell layer

Look at the differences in neuronal sizes between the three layers of neurons shown above.


Bio 240 histology review nervous tissue

Dorsal root ganglion

Spinal ganglion – section – silver – 4x objective

The dorsal root ganglion consists of nothing but the cell bodies of sensory neurons.


Bio 240 histology review nervous tissue

Dorsal root ganglion

Spinal ganglion – section – silver – 40x objective

Sensory neurons are pseudounipolar, so it is hard to see dendrites, axons, and central processes.


Bio 240 histology review nervous tissue

Features of nerve fibers

Nerve – longitudinal section – H&E – 4x objective

The nuclei you find in this section are those of Schwann cells (neurolemmocytes).

With the H&E stain, nerve fibers don’t stain, but the Schwann cells do. Nodes of Ranvier and the myelin are much more easily seen with an osmium stain.


Bio 240 histology review nervous tissue

Features of nerve fibers

Nerve – teased fibers – osmium – 20x objective

node of Ranvier

Osmium stains the lipid of myelin gray-black. The segments you see are individual pieces of myelin. Between each would reside nodes of Ranvier.


Bio 240 histology review nervous tissue

Structures of a nerve in cross section

Artery, vein, and nerve – cross section – H&E – 4x objective

nerve

vein

artery

Oftentimes, an artery, its two companion veins, and a nerve will travel together bundled into a common connective tissue.


Bio 240 histology review nervous tissue

Structures of a nerve in cross section

Artery, vein, and nerve – cross section – H&E – 10x objective

fascicles

This nerve is formed of 4 fascicles (individual bundles of fibers)


Bio 240 histology review nervous tissue

Structures of a nerve in cross section

Perineurium – invests an individual fascicle, holding the nerve fibers together as a single fascicle

Epineurium – invests all the fascicles, holding them together as a single nerve

Endoneurium – extensions of the perineurium that invest each individual nerve fiber within the fascicle

Artery, vein, and nerve – cross section – H&E – 10x objective

This nerve is formed of 4 fascicles (individual bundles of fibers)


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