DETECTION AND CHARACTERISTIC OF FLAT ERYTHROID COLONIES IN SEMISOLID CULTURAL MEDIUMS

It have been shown that progenitor cells of cord blood, bone marrow and ?mobilized? peripheral blood in semisolid mediums gave flat erythroid colonies. These colonies are able to form one or more red centers on the 14th day of cultivation and get a big size that evidence about high proliferative activity and resemble granulocyte, erythrocyte, monocyte/macrophage, megakaryocyte colony-forming units. However 92% of the cells of flat colonies express CD235. It shows that the colonies are erythroid, although colony morphology differs from burstoforming erythroid units and erythroid colony forming units. Their occurrence probability in methylcellulose-containing medium is 2,5%±1%, that is significantly lower than in agar- containing medium (58%±4,8%). Thus, we suggested that flat colonies should be counted separately or they should be ascribed as BFU-E.