Deuterium oxide: direct action on sympathetic ganglia isolated in culture.

Immature ganglia from chicks and rodents were maintained as organized, developing cultures for 2 months or more, during which time they were continuously exposed to deuterium oxide in their medium. Observations of the living cell communities with the light microscope indicated that deuteration within viable limits (up to 25 percent) accelerates and increases the growth of sympathetic neurons and favors their repeated subdivision as a very large size is attained, thus inducing them to recapitulate cyclically the early stages of neurogenesis. Living deuterated cells appear more opaque and heteromerous than control neurons; furthermore, electron micrographs reveal an unusual abundance of granular and fibrillar elements in the nuclei of both neurons and supporting cells. Sheaves of complexly organized fibrillar components appear in the neuronal perikaryon; and ribosomes, Golgi elements, and microtubules are conspicuously numerous. Both fine structure and function of these ganglia therefore appear to have been modified directly by action of the deuterium isotope.