The liver plays an important role in the production of haemopoietic hormones. It acts as the
primary site of synthesis of erythropoietin (EPO) in the fetal stage, and it is the predominant
thrombopoietin (TPO)-producing organ for life. In contrast to that of EPO and other liver
proteins, the hepatic synthesis of TPO is influenced little by external signals. Hepatocytes
express the TPO gene in a constitutive way, ie irrespective of the level of platelets in blood.
Megakaryocytes and platelets remove the hormone from blood by means of their high …