Morphologic and quantitative evaluation of bone marrow aspirates from Hispaniolan Amazon parrots (Amazona ventralis)

Left shift and toxic change in heterophils and neutrophils of non-mammalian vertebrates: A comparative review, image atlas, and practical considerations

Heterophils and neutrophils are important first cellular responders to inflammatory conditions. In addition to quantitative shifts in the numbers of these cells in blood, inflammatory disease states often have accompanying increases in immature precursor stages (left shift) and/or evidence of toxic change on blood film evaluation. Recognition of left shift and toxic change morphologies is a salient diagnostic finding with clinical relevance across species. The objectives of this report are to (a) review heterophil and neutrophil function and structure across the vertebrate animal kingdom, (b) compare morphologic features of left shift and toxic change in heterophils and neutrophils of non-mammalian vertebrates (NMV) to mammals, (c) provide an image guide demonstrating the breadth of morphologic diversity of heterophil and neutrophil lineages in health and disease across taxa, and (d) discuss practical considerations for clinical pathologists and other professionals involved in the recognition and interpretation of observations in the inflammatory leukogram of NMV.

Three-Dimensional Avian Hematopoietic Stem Cell Cultures as a Model for Studying Disease Pathogenesis

Three-dimensional (3D) cell culture is attracting increasing attention today because it can mimic tissue environments and provide more realistic results than do conventional cell cultures. On the other hand, very little attention has been given to using 3D cell cultures in the field of avian cell biology. Although mimicking the bone marrow niche is a classic challenge of mammalian stem cell research, experiments have never been conducted in poultry on preparing in vitro the bone marrow niche. It is well known, however, that all diseases cause immunosuppression and target immune cells and their development. Hematopoietic stem cells (HSC) reside in the bone marrow and constitute a source for immune cells of lymphoid and myeloid origins. Disease prevention and control in poultry are facing new challenges, such as greater use of alternative breeding systems and expanding production of eggs and chicken meat in developing countries. Moreover, the COVID-19 pandemic will draw greater attention to the importance of disease management in poultry because poultry constitutes a rich source of zoonotic diseases. For these reasons, and because they will lead to a better understanding of disease pathogenesis, in vivo HSC niches for studying disease pathogenesis can be valuable tools for developing more effective disease prevention, diagnosis, and control. The main goal of this review is to summarize knowledge about avian hematopoietic cells, HSC niches, avian immunosuppressive diseases, and isolation of HSC, and the main part of the review is dedicated to using 3D cell cultures and their possible use for studying disease pathogenesis with practical examples. Therefore, this review can serve as a practical guide to support further preparation of 3D avian HSC niches to study the pathogenesis of avian diseases.