"biomedicalephemera :      Blood cells; Erythrocytes, Leukocytes, and Platelets (thrombocytes).    ""Normoblasts"" are the immediate precursor to erythrocytes (red blood cells) - they're essentially an erythrocyte that still maintains a cell nucleus.   The ""transitional form"" is a transitional white blood cell.    Normal Histology, With Special Reference to the Structure of the Human Body.  George A. Piersol, 1910."