ABSTRACT
The most immature progenitor of the erythrocyte of the mature bird is a round cell with a spherical nucleus and whose cytoplasm has yet to demonstrate the presence of hemoglobin. This cell’s rather stepwise maturational evolution to the adult configuration and its synthesis and accumulation of hemoglobin is a well documented, important phenomenon of hematology. The morphologic maturational sequence of the avian erythrocyte is the same as observed in the evolutionary antecedent Chondrichthyes, Osteichthyes, Amphibia and Reptilia. The succeeding level of maturation, the one in which the production of hemoglobin is visually increasingly obvious, is the rubricyte. The first cell of the series is the most immature reticulocyte because it presents the greatest amount of precipitated ribonucleoprotein. The developing avian erythroblast undergoes repeated mitoses during its maturation. The reticulocyte is included in the maturational sequence of the avians’ and other inframammalians’ erythrocytes.
