Erythroplastids of Duck Blood Produced by Cytokinesis, Lysis, and Amitosis

The aim is to describe anuclear erythrocytes (erythroplastids), pyrenocytes (small nucleated daughter erythrocytes), and amitosis (division without chromosomes or a spindle apparatus) of the commercial duck. Wright-Giemsa-stained blood samples came from ducks between 2 and 22 weeks of age. The erythroplastids and pyrenocytes were produced by fully hemoglobinized (normochromic) erythrocytes, and their earlier developmental stages (polychromatic erythrocytes). The cytokinesis results indicated a process beginning with constriction of the cell membrane, and continuing with constriction of the nucleus; followed by its polar displacement and expulsion. Instances of intermediate stages in which both the erythroplastid and the pyrenocyte remained attached by a thin cytoplasmic isthmus were also found. Erythroplastids may be produced by a second mechanism where the RBC nucleus lyses rather than being expelled. Furthermore, there were examples of erythroplastids produced during amitosis, occurring in mature erythrocytes, and at earlier (polychromatic) stages. The causes of erythroplastid formation and amitosis remain obscure, and it is possible that they result from distinct stimuli. As Goncalves et al. (2020) reported, recently erythroplastids were used to measure the effects of air pollution in passerine birds. However, as is the case for other atypical erythrocytes they could be the consequence of toxins, DNA damage, vitamin deficiencies, or immune dysfunction. Erythroplastids and amitotic cells were present along with evidence of fungal infection in some ducks and in others deliberately exposed to aflatoxin B1 supporting a case for toxicity. Accordingly, these atypical cells may serve as sensitive cytological indicators and bio-markers useful in the study of diseases or toxin exposure.