A comparison of three-dimensional growth characteristics of cultured primitive marrow stroma derived from genetically...

This study examines the ultrastructure of mouse defective marrow stroma when cultured as a three-dimensional organization of cells. Gelfoam sponges impregnated with agar medium allowed the three-dimensional organization of newly formed stromal cells derived from the crevices of marrow-depleted bones of Steel mutant mice (Sl/Sld) with defective stroma and also from mice with normal stroma (Sl +/+, W/Wv, and W +/+. Ultrastructural comparisons of 5- to 14-day cultures revealed that the mutant defective stromal cells developed normally, viz. i) proliferated and formed a three-dimensional organization of stroma, ii) stimulated residual hemopoietic precursors to form myeloid cells, and iii) formed a variety of stromal cell types characterized by variable quantities of Golgi bodies and ER, glycogen, filaments, and round cytoplasmic granules. The Steel-Dickie strain, however, included bacilliform electron-dense granules in both normal and mutant stroma. The only ultrastructural deficiency in Sl/Sld stroma was the absence of a category of "activated" cells that occurred within normal cell populations.