New Methylene Blue Stain, 500x

Reticulocytes in a feline blood smear

In the cat, we can observe two types of reticulocytes: aggregate reticulocytes (red arrow) and punctate reticulocytes (black arrow). However, it is the aggregate reticulocytes which must be counted when evaluating anemia for a regenerative response, because these are only found in the circulation for 24 hours, therefore reflecting the current activity of the bone marrow. Punctate reticulocytes, on the other hand, can remain in circulation for up to three weeks. Aggregate reticulocytes can be identified by their linear aggregates of ribosomes, rather than individual (punctate) structures as seen in punctate reticulocytes.