present in peripheral nerves. Label Aindicates skeletal muscle, identifiable
by its striations and peripherally located nuclei.
145.The answer is e.(Sadler, pp 286, 290–291, 311, 313, 315. Junqueira,
p 155. Kandel, pp 880, 883, 1027, 1046–1048. Moore and Persaud, Developing,
pp 90, 202, 303–304, 428–435, 486–487, 494, 522.)The neural crest forms
most of the peripheral nervous system, in contrast to the neural tube, which
is the embryonic source of the central nervous system. The sensory neurons
of the cranial and spinal sensory ganglia (e.g., dorsal root ganglia), sympa-
thetic chain ganglia, postganglionic sympathetic and parasympathetic fibers
of the autonomic nervous system, cells of the pia and arachnoid, Schwann
cells, and satellite cells of the dorsal root ganglia are neural elements derived
from the neural crest. Nonneuronal structures formed from the neural crest
include melanocytes of the skin, odontoblasts in teeth, derivatives of the
branchial arch cartilages (e.g., pinnae of ear), and the adrenal medulla, but
not the adrenal cortex, e.g., zona granulosa (answer a).The adrenal
medulla represents postganglionic sympathetic fibers that respond to inputs
from preganglionic sympathetic fibers in splanchnic nerves. Ventral horn
and pyramidal cells (answers b and c)as well as astrocytes (answer d)are
derived from the neuroepithelium of the neural tube.
146.The answer is b.(Junqueira, p 179. Ross and Pawlina, p 336. Kasper,
p 140. Kumar, p 1356.)The structure in the photomicrograph delineated by
the arrow is a single intramural parasympathetic ganglion cell distinctly
characterized by its large, euchromatic nucleus and prominent nucleolus.
Several small satellite cells surround the ganglion cell. Parasympathetic
stimulation of the salivary glands produces a profuse, watery secretion.
Atropine blocks parasympathetic responses. The child in the scenario is
suffering from cerebral palsy (CP). Sialorrhea is excessive drooling and is a
common symptom in children with CP. Children with CP are at increased
risk of aspiration, skin maceration, and infection. Sialorrhea also impedes
social integration. Parasympathetic ganglia are located in close proximity to
or in the wall of the organs they innervate. Other structures within the field
include serous acini from an exocrine gland, a small peripheral nerve, a
venule, and several skeletal muscle fibers.
147.The answer is d.(Junqueira, pp 45, 47, 153–154, 160–163.)The cells
labeled with GFAP are activated astrocytes. Astrocytes are the most abundant
cell type in the human brain. Astrocytes are activated following CNS damage
Nervous System Answers 247