Abstract
The fluorophores formed from catecholamines in certain fiber structures are easily extracted from their tissue sites by xylene or hot paraffin, in contrast to the fluorophores in the ordinary adrenergic nerve fibers, which are fairly resistant to such media. A modified histochemical procedure is described, which reduces to a minimum the exposure of the specimens to hot paraffin and xylene. With this procedure, a higher sensitivity and reproductiveness of the fluorescence method is achieved in many structures. Thus hitherto unknown monoamine-containing structures have been detected, e.g., in the mammalian pituitary gland.