An Evaluation of Host Cell Contact in the Regulation of Diffusion Chamber Hematopoiesis

Micropore membranes used for diffusion chamber studies of hematopoiesis have been examined by electron microscopy after 9 days of culture to see if these membranes exclude contact between cytoplasmic processes of host cells and implanted cells. No penetration of membranes with 0.1- or 0.22-μm pore size was observed, and only shallow penetration of 0.45-μm membranes was observed. Intact cells traversed 0.8-μm membranes. Cell growth was comparable in the chambers constructed with 0.1-, 0.22-, and 0.45-μm membranes. Marrow cells did not grow in diffusion chambers that were prevented from establishing close contact with host membranes.