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Lymphocytes respond to chemical or pathological challenges by synthesizing episomes or extrachromosomal DNA (eDNA). Phytohemagglutinin (PHA) is a mitogen for T lymphocytes and can stimulate the increased production of episomes as well as the release of eDNA, interleukin-2, and other factors. However, the origin of this eDNA is largely unknown. To confirm the observation on the localization of an antibody directed against a 23-kb segment of bull acrosomal DNA in cultured human lymphocytes, we performed analyses by fluorescence in situhybridization (FISH) using the same DNA as a molecular probe.

Brain and ganglia of embryonic Periplaneta americanawere grown for 2 to 3 weeks in a chemically defined medium. Nerve fibers sprouted vigorously from intact brains and ganglia, interconnecting nerve cultures, and adjacent cultures of the digestive tract, Glia, tracheal, and nerve cells were present in large numbers in the migratory zone surrounding the explants.