Abstract
Outgrowth of rat pineal tissue in diffusion chambers began with a migration of connective tissue cells from the implant, and this was followed by a spreading of the parenchymal cells to the margins of the chambers.
Diffusion chamber implants and fresh slices of pineal organ were incubated for monoamine oxidase (MAO) in a medium containing nitro-blue tetrazolium and tryptamine hydrochloride. The MAO reaction was visualized as black formazan granules in parenchymal cells of all cultures throughout the entire 21 day observation period. These cytoplasmic granules appeared to increase in number and in size during the later time periods. A positive enzyme reaction also was present in slices of fresh pineal organ treated in the same medium and in a medium without the substrate, tryptamine hydrochloride. Pineal tissues with prior treatment in a MAO inhibitor gave a negative reaction.
Some parenchymal cells in diffusion chamber implants accumulated many large lipid droplets. There were fewer of these cells than MAO positive cells, and they appeared to migrate from the implant at a slower rate.