Reticulocytes are immature erythrocytes that contain organelles that are lost as the cell matures. These organelles clump into visible granules referred to as reticulum when stained with NMB
Cats, unlike any other species, demonstrate 2 morphologic forms of retics. The aggregate form contains large clumps of reticulum and is similar to reticulocytes found in other species. The punctuate form, which is unique to cats, contains 2 - 8 small, singluar, basophilic granules.