Key result
Injection of poliomyelitis virus into medullated peripheral nerves of monkeys demonstrates that its spread to the central nervous system is likely stopped by the myelin sheath.
The spread of poliomyelitis virus to the central nervous system is resisted by the myelin sheath of peripheral medullated nerves.
The dictum has been formulated that poliomyelitis virus has an almost obligate affinity for gray nerve fibers.1When the virus is injected into medullated peripheral nerves of a normal Macaca mulatta monkey its spread is resisted, unless there has been previous manipulation whereby gray-fibered axis-cylinders have become exposed.2Even under these conditions, the disease is difficult to produce. It may be concluded, therefore, that poliomyelitis virus has but a slight affinity for the exposed axons of peripheral medullated nerves, and, by inference, it might be deduced that its spread to the central nervous system is stopped by the myelin contained in the sheath which covers the gray fibers. This would explain why there is not in every case of poliomyelitis involvement of the vagus nerve, which is actually a bundle of well medullated connector fibers, the postganglionic unmedullated gray fibers of which are found in the walls of
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John A. Toomey (1940) studied Poliomyelitis. Injection of poliomyelitis virus into medullated peripheral nerves was evaluated on Spread of virus to the central nervous system. Injection of poliomyelitis virus into medullated peripheral nerves of monkeys demonstrates that its spread to the central nervous system is likely stopped by the myelin sheath.
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