Wright's stain, 500x
Metarubricytes are erythroid precursors possessing a pyknotic (or apoptotic) nucleus, the last stage of maturation before the erythrocyte losses its nucleus. In a healthy animal, a blood smear will contain few metarubricytes, however, the number will increase in conditions such as regenerative anemia, or lesions in the spleen or bone marrow as well as other diseases.
The black arrow indicates a metarubricyte and the red arrow illustrates two polychromatophils. This is a case in which the metarubricytes accompany a regenerative anemia.