PS 37 - Dorsal Root Ganglion (DRG) (MS 15 400X)

Note the following features in this PS of a spinal ganglion:

1. Large, ovoid cell body (cyton) 2. Tendency for nucleus to be centrally located 3. Prominent axon hillock (arrow) 4. Single axonal process (arrow) 5. No dendritic processes - fused with proximal part of axonal process 6. A pseudounipolar neuron 7. AMPHICYTES (capsule or satellite cells). Single layer of cuboidal cells with ovoid nuclei which surround cyton. 8. Artifact - space between cyton and amphicytes 9. The area between cytons a. Nerve fibers b. Delicate reticular connective tissue c. Small blood vessels d. Cells associated with the nerve fibers 10. Identify the above features in MS 15.

Autonomic Ganglia (Motor Ganglia)

A. LOCATION 1. SYMPATHETIC a. PARAVERTEBRAL 1) Located at regular intervals along sympathetic trunk 2) Examples: chain ganglia, cranial and caudal cervical, cervicothoracic (stellate) b. PREVERTEBRAL 1) Located along ramifications of sympathetic nerves, usually associated with viscera. 2) Examples: celiac, cranial and caudal mesenteric, adrenal, renal. 2. PARASYMPATHETIC (Terminal ganglia) a. Located in or near the organ they serve. b. MYENTERIC PLEXUS (Auerbach's) - between layers of smooth muscle coat of viscera. c. SUBMUCOSAL PLEXUS (Meissner's) - in submucosa (connective tissue) of wall of viscera. d. Ciliary ganglion - serving eye B. FUNCTION 1. SYMPATHETIC a. Impulses originate from cell bodies in lateral horn of thoracolumbar region of the spinal cord. b. PREGANGLIONIC FIBERS extend from CBO to synapse with second cell body in either a paravertebral or prevertebral ganglion. c. POSTGANGLIONIC FIBERS from second cell body to termination on organ served. d. Concerned with "fight or flight" response. 2. PARASYMPATHETIC a. Impulse originates from CBO in brain stem or sacral region of spinal cord. b. Preganglionic fibers extend from CBO to synapse with second cell body in parasympathetic ganglia (usually within the organ). c. POSTGANGLIONIC FIBERS extend from cell body in ganglion to area of viscera to be activated. Post ganglionic parasympathetics are typically very short. d. Concerned with day-to-day vegetative functions. 3. GENERAL INFORMATION a. Two neurons are required to convey an autonomic impulse from CNS to organ served. b. Most organs are supplied by both sympathetic and parasympathetic nerves. c. Motor action of the sympathetic and parasympathetic systems are generally antagonistic (one system speeds activity; the other slows activity).

Morphology

Sympathetic Ganglia