The right answer is Myelocytes
Myelocytes are immature cells of the granular line (eventually forming granulocytes, a type of white blood cell).
In the basal state, myelocytes are only found in the bone marrow, where granulocytes (also called polynuclear cells) are matured.
The maturation of granulocytes is referred to as granulopoiesis. Granulopoiesis represents part of the hematopoiesis and leads to three types of mature granulocytes: neutrophils, basophils, and eosinophils. All hematopoietic cells are derived from hematopoietic stem cells.