The segmented neutrophil is the end stage of maturation in the myeloid lineage. The cell is similar in size to the band neutrophil and has a well-granulated cytoplasm with a deeply condensed, knotted, and clumped chromatin pattern. The chromatin pinches into several segments, usually separated by visible filaments. In some segmented neutrophils, this filament is inferred by the folding and shape of the nucleus.
The top image on the right shows the classic morphology of a segmented neutrophil. The nucleus of a normal segmented neutrophil has two to five lobes, connected by thin filaments. Six or more lobes are an indication of abnormal development, usually related to B12 or folate deficiency.
The bottom image shows the progression from band neutrophil (red arrows) to early segmented neutrophil (blue arrow) and finally to fully-mature segmented neutrophil (green arrow). Take a close look at the cell closest to the promyelocyte. You can see a drumstick-like projection arising from the end terminal segment. This can be seen in smears on female patients and is a Barr body or inactivated X-chromosome.
