ELECTRON MICROSCOPICAL DEMONSTRATION OF ACID PHOSPHATASE IN BLOOD PLATELETS

Ultrastructures of human and rabbit thrombocytes reveal specific subcellular organelles within these elements. Serotonin granules are demonstrated containing extremely electron opaque material in vesicles with an average diameter of 1,700 Å and a considerable number of large dense bodies (average size 4,000 Å in diameter) is seen. The latter are less electron dense as compared to the serotonin granules. The appearance of serotonin granules in the human thrombocyte is rare, while rabbit platelets show a higher number of these granular vesicles. Acid phosphatase activity in the large dense bodies of human and rabbit platelets has been demonstrated by means of electron microscopy. Present results together with currently available biochemical information are briefly discussed in relation to the lysosomal activity within the thrombocytes. © 1969 Springer-Verlag.