Rough Endoplasmic Reticulum and Ribosomes in Blood Platelets

Abstract

Rough endoplasmic reticulum (RER) and free ribosomes were rarely present in blood platelets of normal rabbits or human subjects. After thrombin infusion or bleeding, rabbits became thrombocytopenic and the relative number of platelets containing RER and polyribosomes was considerably increased. The presence of RER in isolated platelets provides a morphological basis for protein synthesis. The increase in ribo‐some‐containing platelets after induction of thrombocytopenia suggests that these elements are derived from young megakaryocytes.