I.S. Raginov Dr.Sc. (Med.), Head of Department of Pathology Republican Clinical Hospital, Associate Professor, Department of Histology, Kazan State Medical University, Kazan, Russia. E-mail: raginovi@mail.ru G.V. Vafina Post-graduate Student, Department of Histology, Kazan State Medical University, Kazan, Russia V.I. Egorov Ph.D. (Vet.), Head of Department of Veterinary Pharmacology, FCTRBD-VNIVI, Kazan, Russia M.V. Lekishvili Dr.Sc. (Med.), Head of Laboratory «Tissue Bank», N.N. Priorov Research Institute of Traumatology and Orthopaedics, Moscow, Russia. E-mail: leki@mail.ru