[Are the lungs a thrombocytopoietic organ?].

Platelets are the small circulating cellular elements. They play a very important role in hemostasis. In the opinion of some investigators platelets are not true cells. We present current hypothesis about development and regulation of megakaryocytopoiesis in the bone marrow and the lung production of platelets. Megakaryocytes are present in central venous blood. In the lung platelets are derived from the cytoplasma of megakaryocytes but they are not produced by mitosis but by sequence of binary division at the dichotomous branches of the pulmonary microcirculation. Naked nuclei and platelets are in arterial blood.