From left to right, the images represent increasing stages of maturity of canine neutrophils. The first identifiable specific neutrophil precursor is the myelocyte, which differentiates into a metamyelocyte, then a band neutrophil and finally a mature segmented neutrophil. These stages have similar cytoplasmic features and are primarily differentiated by the shape of the nucleus (round in a myelocyte, kidney bean-shaped in a metamyelocyte, horse-shoe-shaped in a band, and classically segmented in a mature neutrophil. Note the band also has evidence of toxic change (cytoplasmic basophilia and vacuolation), whereas the other stages are not toxic. The immature neutrophils are deliberately depicted to the left of the mature neutrophils (in sequential order) to illustrate the use of the term “left shift”.
