1. Institute of Veterinary-Anatomy, -Histology and -Embryology; University of Giessen; Frankfurter Str. 98. 35392 Giessen Germany
2. Anatomy and Embryology Department; Faculty of Veterinary Medicine; University of Mansoura; 35516 Egypt
3. Department of Veterinary Clinical Sciences; Small Animal Clinic c/o Institute of Veterinary Anatomy, Histology and -Embryology; University of Giessen; Frankfurter Str. 98. 35392 Giessen Germany