Meeting Abstract

P3-148   -   They blow up so fast: Development of pneumatic air spaces in the humerus of domestic and wild turkeys Ward, AF; Wilson, EA; Gutherz, SB; O'Connor, PM; Rohlf, P; Stover, KK*; West Virginia School of Osteopathic Medicine; West Virginia School of Osteopathic Medicine; Ohio University; Ohio University; Aviagen Turkeys, Inc.; West Virginia School of Osteopathic Medicine kstover@osteo.wvsom.edu

Postcranial skeletal pneumaticity is a feature unique to birds among extant tetrapods in which the respiratory system infiltrates bones and replaces internal bone tissues (e.g., marrow) with air. Whereas the presence of pneumaticity has been characterized in a diverse array of birds, few studies have documented the development of skeletal pneumaticity. Using pre-existing data, we measured the internal air space in humeri of developing turkeys (Meleagris). Individual turkeys were CT scanned in vivo at several time points, with domestic turkeys scanned between 10-18 weeks of age (n=4 for each of 2 lines) and wild turkeys (n=8) scanned between 2-20 weeks. CT data were segmented using 3D visualization software to estimate air and whole bone volume. We then calculated ratios of air volume to whole bone volume, or air space proportion (ASP), and assessed changes in ASP through the growth series, as well as its relationship to whole bone volume. Whereas the humerus exhibited a steady increase in volume throughout the scanning interval, we observed a rise in internal air volume and ASP followed by a decline in most individuals. Peak ASP occurred at ~10 weeks in the wild turkey and ~15 weeks in the domestic turkey. The right and left humeri exhibited asymmetric pneumatization patterns in most individuals, with a disparity between sides of up to 27% in the wild turkey and 15% in the domestic turkey. All domestic turkeys featured pneumatic humeri in at least one scan whereas 75% of the wild turkeys exhibited pneumatic humeri at some point. Pneumaticity first appeared proximally at the shoulder joint and progressed distally down the humeral shaft to varying degrees. This pilot study is necessary for understanding the basic temporal and spatial progression of epithelial invasion of the avian postcranial skeleton and development of adult pneumaticity phenotypes.