Histological study of the syrinx in swan goose (Anser cygnoides)

The current exploration was done to study the histological characteristic features of the syrinx in the swan geese (Anser cygnoides). For that purpose, 10 (5 males and 5 females) birds were euthanized and specimen was collected for studying the location, length, and relationship were reported. Moreover, the syrinx was histological-studied by hematoxylin and eosin (H&E), Periodic acid–Schiff stain (PAS), combined Alcian blue (AB) and PAS, and Masson's trichrome and Verhoeff stain. The results unveiled that the voice box (syrinx) of the swan goose revealed that the syringeal wall thickness was (1903.78±2.957 and 1902.5±1.476µm), for males and females, respectively. The part of the tracheosyringeal rings were ciliate-lined of pseudostratified columnar epithelium with different-sized acini in high numbers (tubular mucous glands), and epithelia-linedgoblet cells. The mean thickness of the epithelium was (204.56±2.231 and 198.92±1.513µm) in males and females, respectively. The average thickness of the cartilage was (207.78±1.601 and 199.12±1.661µm) in males and females respectively. Simple branched mucous glands showed a positive reaction to the PAS stain. Also, positive reaction for alcian blue and combined alcian blue pas stains. The diameter of the syringeal mucous alveoli was 304.02±3.205 and 298.02±4.072µm in males and females respectively. This study reveals the characteristic pictures of the syrinx of the swan geese that could be useful for future studies that deal with different sciences, such as public health and industries of this bird.