Air sacs (Sacci pneumatici) in mallard ducks (Anas platyrhynchos)

This study aimed to observe the air sacs (Sacci pneumatici) in mature Mallard ducks (Anas platyrhynchos). After animals (n=9) were euthanased by combination of ketamine 60 mg/kg and xylazine 6 mg/kg, methylmethacrylate (Takilon) was injected by way of trachea. They were put in a cold-aired room for two months for polymerization. Then, they were maserated with 3% potassium hydroxide at 40 °C, cleaned with tap water, coloured by glass dye and photographed. Morphology of the cervical and clavicular air sacs was consistent with previous studies. The cranial thoracic air sacs were smaller than the caudal sacs pneumatising the second to seventh ribs by their diverticula. The caudal thoracic air sac had no diverticulum. The left abdominal air sac had two portions, i.e. the cranial and caudal sacs; the latter aerating the last three ribs and synsacrum, the former being smaller and narrower. Moreover, the right abdominal air sac was bigger than the left sac.