Eosinophils basically go through the same maturation stages as neutrophils. However, they are only recognizable as a eosinophils if specific eosinophilic granules occur. This is the case only from the myelocyte stage on. Since nuclear maturation does not occur immediately, immature eosinophils are distinguished from mature eosinophils in bone marrow. They constitute about of nucleated bone marrow cells (myelogram).
Mature eosinophils cannot be distinguished morphologically from peripheral blood eosinophils. They usually have bilobated nuclei and packed orange granules which do not cover the nuclei.