Practical lesson №1
Theme: Spinal ganglion, peripheral nerve.
Spinal cord.
Learning objectives:
1.To learn to identify tissue elements of the peripheral and central nervous system at the
microscopic level
2.To learn to distinguish the bodies of the peripheral and central nervous system based on the
microscopic structure
3. To know the peripheral organs and the central nervous system based on its microscopic
structure.
4.To know the tissue elements of the peripheral and central nervous system at the microscopic
level.
5. To know the structure of the spinal cord.
6. Role of spinal ganglia neurocyte in the reflex arc.
7.The structure of the spinal ganglion, it neurocytes and glial cells. Location and nature of
neurocyte ganglion.
8. The structure of autonomic ganglia, the nature of the location and types of neurocyte.
9. The concept of nerve fibers and their structural elements.
10. To know the cytologic features of nerve cells (nerve fibers) atmicroultramicroscopic level.
Nervous system development
The central nervous system(CNS) is derived from the
ectoderm- the outermost tissue layer of the embryo. In
the
third
week of
human
embryonic
development the neuroectoderm appears and forms
the neural plate along the dorsal side of the embryo.
The neural plate is the source of the majority of
neurons and glial cells of the CNS. A groove forms
along the long axis of the neural plate and, by week
four of development, the neural plate wraps in on itself
to give rise to the neural tube, which is filled
with cerebrospinal fluid(CSF). As the
embryo
develops, the anterior part of the neural tube forms
three primary brain vesicles, which become the
primary anatomical regions of the brain: the forebrain,
midbrain, and hindbrain.
Spinal ganglion
Dorsal root ganglion is an aggregation of sensory
neurons (pseudo-unipolar) located on each dorsal
spinal root.
Ganglion cells - large, nerve cell bodies with
centrally located nuclei
Nucleolus - intensely stained because it contains
negatively charged RNA involved in ribosome
assembly
Nissl (chromophill) Substance - contains negatively
charged RNA found in free ribosomes and ribosomes
bound to endoplasmic reticulum (i.e., RER)
Only found in cell body and dendrites
Abundant chromophil substance suggests these neurons
synthesize large amounts of protein
Satellite (or Capsule) Cells - small, glial cells at
the periphery of nerve cell bodies
Nerve fibers - unmyelinated and myelinated axons
of different diameters
Mylenated Fibers - unstained because lipids of the
myelin sheaths were extracted during staining (appears
foamy)
Epineurium - fragments of dense irregular connective
tissue that surround nerves
Spinal ganglion.
Hematoxylin-eosin.
Х400
1Capsule of the spinal
ganglion;
2 Pseudounipolar
neurocytes;
3Satellite cells (cloak
gliacytes);
4Myelinated nerve
fibres.
SPINAL GANGLION
Hematoxylin- eosin.
1- body of the neuron
2- mantle gliocytes
3- capsule
Spinal ganglion
•
•
•
•
1 – dorsal root
2 – spinal ganglion
2.1 – capsule
2.2 –
pseudounipolar
neurons
• 2.3 – nerve fibers
• 3 – ventral root
• 4 – spinal nerve
Transverse
section of the
spinal cord
Silver impregnation. X 40.
1 – anterior median
fissure
2 – anterior funiculus
3 – anterior horns
4 – lateral funiculus
5 – lateral horn
6 – posterior horn
7 – posterior funiculus
8 – central canal
9 – posterior grey
commissure
10– anterior grey
commissure
Anterior horn
of the spinal
cord
1 – motor neurons
2 – white matter
3 – transverse
section of the
nerve fibers of the
white matter
4 – septa
Spinal cord
A drawing of a transverse section through the T10 spinal segment is shown on the
right. The spinal cord is bilaterally symmetrical. Ventrally, the halves are separated by
a ventral median fissure (into which pia mater invaginates). Dorsally, spinal halves are
demarcated superficially by a dorsal median sulcus. Deep to the sulcus, a dorsal median
septum (caudally a fissure) separates the halves. Bilaterally a dorsolateral sulcus marks the
entry site of dorsal rootlets into the spinal cord. At the center of the section, the central
canal is lined by ependymal cells and surrounded by butterfly-shaped gray matter, which is
surrounded by white matter.
With the naked eye and with the scanning objective, identify the centrally located
butterfly or H-shaped arrangements of the gray matter. With the scanning objective identify
the white and gray matter, and the dorsal (posterior) and ventral (anterior) horns of the gray
matter.
With the 10X objective, identify the cell bodies of the large motor neurons in the
anterior horn of the gray matter. Identify the basophilic Nissl substance. Is there Nissl
substance in the dendrites? In the axons? To what structures at the electron microscopic level
do the Nissl bodies correspond?
Within the white matter, note the nuclei of glial cells (mostly oligodendroglia) and
the cross sections of axons (unstained). The clear space surrounding each axon is occupied in
life by the myelin sheath. Note the meninges surrounding the spinal cord. In some slides you
will be able to identify the dorsal and ventral rootlets of the spinal nerves within the
subarachnoid space
Peripheral nerves
In a peripheral nerve, nerve fibers
and their supporting Schwann cells
are held together by connective
tissue organized into three
distinctive components that have
specific morphological and
functional characteristics. The
epineurium forms the outermost
connective tissue of the peripheral
nerve, the perineurium surrounds
each nerve fascicle separately, while
the individual nerve fibers are
embedded in the endoneurium
Connective tissue investments of peripheral nerve. The
diagram demonstrates the arrangement of the peripheral
nerve. A segment of the spinal nerve is enlarged to show the
relation of the nerve fibers to the surrounding connective tissue
(endoneurium, perineurium, and epineurium).
Composition of peripheral nerve
Diagnostics of
histological slides
1. Spinal ganglion.
To draw (№1)
Hematoxylin-eosin. x630.
1Capsule of the spinal
ganglion;
2 Pseudounipolar
neurocyte;
3 Nucleus;
4 Nucleolus;
5Satellite cells (cloak
gliacytes);
6Fibroblasts of the
connective tissue
membrane.
2. Transverse section
of the spinal cord.
(To drow №2)
Silver impregnation.
Х40
1Anterior median
fissure;
2 Anterior funiculus;
3 Anterior horns;
4 Lateral funiculus;
5 Lateral horn;
6 Posterior horn;
7 Posterior funiculus;
8 Central canal;
9Posterior grey
commissure;
10Anterior grey
commissure.
3. Anterior
horn of the
spinal cord.
Transverse
section.
Silver
impregnation.
Х200
1 Motor neurons;
2 White matters;
3Transverse
section of the nerve
fibres of the white
matter;
4 Septa.
4. Transverse section
of myelinated nerve.
Demonstrational slide №1
Osmium impregnation. Х400
1- Perineurium;
2 Endoneurium;
3Transverse section of
myelinated nerve fibres;
4- Blood vessels;
5- Loose fibrous connective
tissue.
Semithin section of human sural nerve fixed in osmium tetroxide. The myelin sheaths are
preserved and stained black.
Perineurium surrounds the nerve fascicle. Streaks of connective tissue originate from
epifascicular epineurium inside the nerve as interfascicular epineurium. Fat tissue and blood
vessels are localized in interfascicular epineurium
5. Spinal
ganglion.
Demonstrational
slide №2
Hematoxylin-eosin.
Х40
1 Ventral root;
2 Myelinated nerve
fibres;
3 Dorsal root;
4 Pseudounipolar
neurocytes.
Control questions.
1. Organs of the central nervous system.
2. Tissue elements of the central nervous system.
3. Structure of neurocytes and gliocytes of spinal ganglia.
4. Location of ganglia and neurons.
5. The structure of the spinal cord.
6. Why are perikarya of dorsal horn neurons smaller than those in the ventral
horn?
7.The central and peripheral nervous system, the relationship between
them.
8.
The structure of the peripheral nerve, characteristic of the nerve fibers in
its composition.
9.
The structure of the spinal ganglion, and its neurocytes andgliocytes.
Layout of neurocyte in the ganglion.
10. The role and place of the spinal ganglia neurocyte in the reflex arc.
11. The structure of autonomic ganglia, the nature of the location and types
of neurocyte.
12.Structure of the spinal cord, neurons and glial in the composition of gray
and white matter. Layout of neurocyte.