[To the 125th birthday of Professor Vyacheslav Konstantinovich Beletsky].

This year marks the 125th anniversary of the famous scientist and pathologist Vyacheslav Konstantinovich Beletsky. The scientific biography of the doctor included the stages of study and diagnosis of infectious lesions of the central nervous system, war pathology and pathomorphology of rheumatism. To a large extent, his professional interests were focused on the problem of the participation of microglia cells in the development of pathological processes in the central nervous system. As an ideological and scientific follower of William Robertson and Pio Rio-Ortega, he created his own system of studying and evidencing of histogenesis of microglia from the mesenchymal embryonic premordium. Applying a complex of histological, pathological, anatomical and embryological research methods, V.K. Beletsky substantiated the doctrine of the so-called mesoglia - the connective tissue (mesenchyme) of the central nervous system.