Electron microscopic and cytochemical observations on the membrane systems of the chicken thrombocyte.

A combined electron microscopic and cytochemical study of the thrombocytes of the mature chicken has demonstrated the existence of two membrane systems, the surface connected system (SCS) and the dense tubular system (DTS). The SCS consists of light tubules and vacuoles which are in continuity with the plasmalemma. A ruthenium red-positive reaction product was observed on the inner surface of this membrane system. Ferritin particles were present in the tubules and the vacuoles of the SCS after the thrombocytes had been incubated in vitro with ferritin. The DTS consisted of the nuclear envelope, the rough-surfaced endoplasmic reticulum, dense tubules and concentric double membrane structures, all of which give a peroxidase-positive reaction. Although actual continuity between the DTS and the SCS of thrombocytes was not observed in this study, close approximation between the two systems was observed at many points. These results are discussed in relation to those from comparable studies of human platelets.