Immature red blood cells normally restricted to the bone marrow and present in the blood stream in very low numbers (0.2-2%). An increase in numbers indicates increased proliferation in the bone marrow, for example following chemotherapy.
In vitro globin chain synthesis studies were effected using the technique of Weatherall et al.: in vitro incubation of reticulocytes in a mixture of amino acids containing tritium-labelled leucine; separation of the globin chains in a Perkin Elmer HPLC apparatus and measurement of the radioactivity of the eluates corresponding to the various peaks by means of a TRI Carb Packard spectrometer; calculation of the a/b ratio.