1. Department of Histology and Embryology, Poznan University of Medical Sciences, 60-781 Poznan, Poland
2. Doctoral School, Poznan University of Medical Sciences, 60-812 Poznan, Poland
3. Department of Diagnostics, Poznan University of Medical Sciences, 60-812 Poznan, Poland
4. Department of Diagnostics and Clinical Sciences, Institute of Veterinary Medicine, Nicolaus Copernicus University in Torun, 87-100 Torun, Poland
5. Department of Anatomy and Histology, Collegium Medicum, University of Zielona Gora, 65-046 Zielona Gora, Poland