What is the term for red cells that begin forming enough hemoglobin to be visible on a Wright-stained bone marrow aspirate smear?

The term for red cells that have started to synthesize significant amounts of hemoglobin, which then become visible on a Wright-stained bone marrow aspirate smear, is known as a polychromatic normoblast. During the development of red blood cells in the bone marrow, the polychromatic normoblast stage is characterized by a mixture of diffuse and condensed chromatin, along with a significant accumulation of hemoglobin. This appearance gives the cells a blue-gray color under the microscope due to the presence of RNA in conjunction with the hemoglobin.

As red blood cells mature, they pass through several stages, namely the proerythroblast, basophilic normoblast, polychromatic normoblast, and orthochromatic normoblast before becoming reticulocytes and finally mature erythrocytes.

It is important to differentiate polychromatic normoblasts from other stages like proerythroblasts, which are earlier in the maturation process and do not yet display the visibility of hemoglobin production. Reticulocytes are immature red blood cells released into the bloodstream and consist of remnants of ribosomal RNA, showing up as a slightly different cell type after leaving the bone marrow.