Photomicrographs of wild-type and IL-6^-/- LTBMCs. Cultures were established from wild-type (A, C, E, G) or IL-6^-/- (B, D, F, H) BM and were maintained in Myelocult M5300 medium containing 10^-6 M hydrocortisone at 32°C, with weekly exchange of half of the medium. Photomicrographs were obtained 1 (A-B), 2 (C-D), 3 (E-F), or 4 (G-H) weeks after initiation of cultures. Original magnification × 100.