Polyblasts

POLYBLASTS (from Greek polys - many and blastano - I produce), "diverse cells". The term P. belongs to Ziegler, but was introduced into histology and pathology mainly by Maximov in 1902 to denote those cells of connective tissue which, in contrast to ordinary sedentary connective tissue cells, fibroblasts or fibrocytes, possess considerable mobility and phagocytosis. According to Maximov's description, these are very polymorphic cells, sometimes flat, round or angular, sometimes elongated, sometimes with processes. Their nucleus has an irregular oval, kidney-shaped, rarely round shape and contains coarse uneven granules of chromatin. The protoplasm has a dense reticular structure, in which there are chondriosomes in the form of short chondrioconts or mitochondria and a well-developed cell center consisting of a group of centrioles, sometimes surrounded by a light field. P. are formed, according to Maximov, from lymphocytes, partly those that have just emigrated from blood vessels, partly those present in the tissue in the form of "wandering cells at rest", by increasing their volume and rounding, and in ordinary, resting connective tissue there are few P., whereas with various irritations of it, especially during inflammation, the number of P. increases very significantly. On the basis of tissue cultures, Maximov expressed the possibility of the further transformation of P. into stable connective tissue cells, fibroblasts, i.e., the participation of P. in the construction of connective tissue. Maximov's doctrine of P. is not universally accepted. Most histologists and pathologists prefer to use the synonymous terms "macrophages" or "histiocytes" instead of the term P. and do not accept Maximov's view of the origin of these elements from lymphocytes and the possibility of their transition into fibroblasts (see Wandering cells, Lymphocytes, Macrophages).