Abstract
Amine storage organelles of aldehyde-fixed rabbit platelets have a strong affinity for uranyl ions before their dehydration and appear highly electron-dense when examined by electron microscopy; both the matrix and membrane of these organelles are intensely stained. This affinity, which is also shown by platelets of other species, including healthy reserpinized platelets, which contain no cytochemically demonstrable amine, show a positive uranaffin reaction. However, platelets and megakaryocytes of strains with storage pool deficiency (low adenosine-5'-triphosphate), including patients with Hermansky-Pudlak syndrome, are uranaffin negative. The cytochemical reaction, probably the result of an interaction between UO2++ ions and phosphate groups of 5'-phosphonucleotides, is also observed in adrenal medulla, sympathetic nerve terminals and ganglion cells, suggesting that the technique will be of considerable value in identification of aminergic neurons and in further elucidation of amine storage mechanisms.