1. Department of Histology and Cell Biology, Faculty of Medicine, Assiut University, Assiut, Egypt
2. Department of Histology and Cell Biology, Sphinx University, New Assiut City, Egypt
3. Department of Anatomy and Embriology, Faculty of Medicine, Assiut University, Assiut, Egypt
4. Department of Histology and Cell Biology, Faculty of Medicine, Aswan University, Aswan, Egypt
5. Department of Histology and Cell Biology, Faculty of Veterinary Medicine, Assiut University, Assiut, Egypt