1. Institute of Veterinary Anatomy, Faculty of Veterinary Medicine; Freie Universität Berlin; Koserstr. 20; D-14195; Berlin; Germany
2. Institute of Poultry Diseases, Faculty of Veterinary Medicine; Freie Universität Berlin; Berlin; Germany
3. Fachtierarztpraxis am Erzberg; Braunschweig; Germany
4. Department of Comparative Biomedical Sciences, School of Veterinary Medicine; Louisiana State University; Baton Rouge; LA; USA