Zakhar Katsnelson — outstanding Russian histologist

The article is a tribute to Zakhar Katsnelson, who was a brilliant histologist, a great teacher, and a man of extraordinary integrity and morality. Zakhar Katsnelson became famous as one of the founders of broad comparative descriptive and experimental research of embryonal histogenesis. The authors of this article were interested in his personality, first of all, because he was their compatriot, born in the small Ural town of Irbit. The article provides biographical information about Katsnelson’s scientific career and outlines his professional activities. The most important of Katsnelson’s theoretical and practical scientific researches are described, such as the analysis of effects of chemical factors on the embryonic and larval development of amphibians, the study of the embryonic development of the suprarenal glands in farm artiodactyls, including the demonstration of the inadequacy of the capsule blastema theory and the proof of cell dimorphism in the suprarenal medulla, etc. Katsnelson’s role in cytological research in the USSR is highlighted. Special attention is paid to his participation in the campaign against the pseudoscientific concept of O.B. Lepeshinskaya, which contradicts the cell theory of R. Virchow. The article describes professor Katsnelson’s pedagogical and methodological activities and his talent as a teacher. The article reviews his works on teaching methodology and the history of morphology, which still play an important role in educating veterinary and medical students.