Nucleic acids and protein synthesis of isolated cells from chick embryonic spinal ganglia in culture

Dissociated monolayer cell cultures of chick embryonic spinal ganglia were set up on collagen‐coated coverslips and incubated in 5% CO2 atmosphere at 38°C. Neurons were maintained in good condition for approximately three weeks and showed regeneration of nerve fibers as well as recovery from chromatolysis to normal Nissl pattern. Synthesis and transport of nucleic acids and protein in neurons and in spindle cells were studied with tritiated precursors by means of autoradiography. Less than 3% (10 of 318) of nerve cells from 12‐day‐old chick embryo spinal ganglia showed tritiated thymidine incorporation, whereas 27% (511 of 1880) of spindle cells from the same source incorporated tritiated thymidine. Thus, under our cultural conditions most neurons did not synthesize DNA. Both neurons and spindle cells incorporated tritiated uridine. Newly synthesized RNA appeared in the nucleus, and after several hours it was distributed over the perikaryon of neurons and the cytoplasm of spindle cells. The label was never found in nerve fibers, even after prolonged tritiated uridine treatment. A conclusion is thus made that RNA is absent in the nerve fibers. In neurons, protein was synthesized only in the perikaryon. Nerve fibers did not show protein synthesis. Newly synthesized protein was transported from perikaryon distally along nerve fibers at a rate of approximately 10 mm per day.