1. Histology Department, Faculty of Veterinary Medicine; Sohag University; Sohag Egypt
2. Laboratory of Cell Biology & Histology, University of Antwerp; Antwerp Belgium
3. Department of Cytology and Histology, Faculty of Veterinary Medicine; Cairo University; Giza 12122 Egypt
4. Department of Anatomy and Histology, Faculty of Veterinary Medicine; Assiut University; Assiut Egypt
5. Department of Histology, Faculty of Veterinary Medicine; South Valley University; Qena Egypt