Histological and cytological technique for the quantitation of cultured human bone-marrow cells:formation of aggregates.

A bone-marrow culture system is described that provides a simple, quantitative and rapid assessment of marrow bone cells in vitro. Aggregation of bone-marrow cells, an in vitro phenomenon, occurs within 24 hr of culture and is observed utilizing Millipore filters. Daily quantitation shows both an increase in the number and a change in the morphology of these aggregates. The maximum number of aggregates is achieved on the 2nd or 3rd day of incubation. Histologically, aggregates are composed of myeloid, mononuclear and mesenchymal fibroblastic cells. Mesenchymal cells form a matrix for apposed mononuclear and myeloid cells. Scanning electron micrographs show intimate cell contact and spreading by the marrow cells. Fluctuation of the absolute numbers of various cell types are observed. The system can be utilized for long-term culture of bone marrow.