Catecholamine-storing cells in the cyclostome heart.

The lamprey heart contains characteristic catecholamine-storing cells in both the atrium and the ventricle. Sufficient circumstantial evidence is available indicating that catecholamines together with protein carbohydrate complexes are contained in these cells within the membrane bound cytoplasmic granules. If the "recepto-secretory function" and "neuroectodermal origin" of these cells are proved, then they may be classified as typical paraneurons.