CHAPTER 7
Nervous Tissue
133
Figure 7-16.
Submucosal plexus (of Meissner).
H&E,
3
136; inset
3
453
The
submucosal plexuses
(
of Meissner
) are located in the
submucosal layer of the intestine (see Chapter 15, “Diges-
tive Tract”). These plexuses are similar to the myen-
teric plexuses in that they are unencapsulated clusters
of
parasympathetic postganglionic motor neurons
;
sen-
sory neurons
, which receive input from chemoreceptors
and mechanoreceptors in the intestinal wall; and
local
circuit neurons
(
interneurons
). The postganglionic motor
neurons may innervate smooth muscle to either increase
or decrease muscle activity and may also innervate secre-
tory cells in the walls of the intestine.
Submucosal
plexus
Submucosal
connective tissue
SYNOPSIS 7-1
Pathological and Clinical Terms for the Nervous System
Ataxia
: Inability to coordinate the muscles properly in the execution of a voluntary movement.
Gliosis
: The multiplication of astrocytes as a response to injury in the brain, as exempliF
ed by the feltwork of astrocytic
cell bodies and processes in a demyelinated plaque of MS.
Glomeruloid vascular structures
: Complex arrays of capillaries that resemble the glomeruli of a kidney, are another
hallmark of the glioblastoma.
Neurof
brillary tangle
: The helical arrangement of abnormally phosphorylated neuroF
laments found in many
hippocampal
and cortical neurons of an Alzheimer patient.
Neuropathy
: A disease involving the cranial or spinal nerves.
Onion bulb
: After repeated cycles of demyelination and remyelination, thin layers of Schwann cell cytoplasm form
concentric circles around a central axon. The appearance of the structure resembles a cross section of an onion bulb and
its nested leaves.
Palisading
: The alignment of viable tumor cells at the edge of a necrotic focus in glioblastoma, a diagnostic hallmark of
this grade 4 (most malignant) astrocytoma, a family of glial tumors derived from the astrocyte.
Plaque
: This word indicates a lesion, in several pathological contexts. (1) An atherosclerotic plaque is the hard, calciF
ed
buildup of fatty material in large arteries, such as the coronary arteries or aorta. (2) A neuritic plaque is the extracellular
knot of phosphorylated axons and dendrites, often with a central deposit of amyloid protein, found in great numbers
in brains of patients with Alzheimer disease. (3) In MS, a demyelinated plaque is an irregular zone of axons, often in a
periventricular location, that have lost their sheaths of myelin.
Type of Ganglion
Cell Body
Arrangement
Cell Body
Characteristics
Satellite Cells
Synapses in
Ganglion
Posterior root
(sensory)
Arranged into groups
within ganglion, cell
bodies variable in size
Round cell body,
central nucleus
Complete capsule of
satellite cells
No synapses
Autonomic
( visceromotor)
Evenly distributed
within ganglion,
uniform in size
Multipolar cell body,
eccentric nucleus
Incomplete capsule of
satellite cells
Numerous synaptic
contacts
TABLE 7-1
Comparison of Posterior Root and Autonomic Ganglia
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