The present study was undertaken in an attempt to explore the spinal cord after injection of a tracer substance into the coeliac plexus. We studied two groups of rabbits weighing 2.0 to 2.3 kg: a normal control group and the experimental group.
The
animals were anesthetized with 20% urethane 7 ml/kg body weight intraperitoneally. To make an injectable mixture of the tracer substance. 0.5 gm of ferric oxide (Iron sesquioxide) was mixed with 2 ml of lactated Ringer's solution just prior to
injection.
In normal control group (N=3), animals were killed after anesthetization by shedding blood and the segment of vertebrae from the 6th thoracic to 11 th thoracic were removed and fixed in 10% formalin solution, the experimental group was subdivided
into a
subgroup of perineurial injection of the tracer mixture to the bilateral coeliac ganglia (the perineurial injection subgroup, N=5), a subgroup of intraneural injection of tracer mixture to the bilateral coeliac ganglia (the coeliac ganglion
subgroup,
N=5) and a subgroup of intraneural injection of the tracer mixture to the bilateral superior mesenteric ganglia (the superior mesenteric ganglion subgroup, N=3).
In the perineurial injection subgroup, the bilateral coeliac ganglia were exposed under surgical microscope and 1 ml of the tracer mixture was injected bilaterally exterior to the perineurial connective tissue of coeliac ganglion, After the
injection,
the abdominal wall was closed and animals were then allowed to rest in the lateral position for 2 hours.
In the coeliac ganglion subgroup and the superior mesenteric ganglion subgroup 0.6 to 0.7 ml of the tracer mixture was injected bilaterally into the coeliac ganglia or the superior mesenteric ganglia. After the injection, the abdominal wall of
the
animals were closed and then allowed to rest in the lateral position for 90 minutes. At the end of experiment, animals of the experimental group were killed by shedding blood and the segment of vertebrae from the 6th thoracic to 11th thoracic
were
removed and fixed in 10% formalin solution. Following decalcification in 50% formic acid, histological study was performed with hematoxilin-eosin(H-E) stain or iron stain in transverse sections and sagittal plane of specimen which was obtained in
one
animal of the coeliac ganglion group.
@ES The results were as follows:
@EN 1. In the perineurial injection subgroup, moderate density of the tracer substance was diffused into the dura mater. There was minimally infiltrated tracer in the area of lateral side of the formatio reticularis and the perivascular space of
the
white matter and pia mater.
2. In the coelic ganglion subgroup many tracer were diffused into the perineurial epithelial space of unmyelinated fibers and around the Schwann's sheath of fibers in the ventral and dorsal roots. The white matter was infiltrated uniformly with
the
tracer substance. There was evidence of diffusion of the tracer substance through the glia limitans of the white matter in the transversely or sagittally sectioned slides.
3. The superior mesenteric ganglion was tightly encased with the connective tissue capsule, thus we experienced moderate resistance to injection of the tracer mixture. There was most extensive diffusion of the tracer substance in the ventral and
dorsal
roots, dorsal horns of the gray matter, the area of lateral side of the formatio reticularis and the remaining whole area of the white matter. And the tracer substance was infiltrated around the peripherally situated cells of gray matter.
Our observation demonstrate that the tightly encased ganglion like the superior mesenteric ganglion is the candidate for paralysis when a neurolytic agent was injected intraneurally.
In discussion we indicated the existance of small ganglion on the wall of abdominal aorta which is prone to produce paraplegia of the distal extremities in case of neurolytic coeliac plexus block.
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