Distribution of BM-derived GFP-positive cells after GFP-positive BM plus WT intestine transplantation. (A) Flow cytometric analysis of lymphoid organs in recipients of WT intestine plus GFP-positive BM at day 120. From 4% to 6% of GFP-positive cells were seen in the mesenteric lymph nodes (MLN) and Peyer patches (PP) of WT intestine grafts. Host spleen (sp), cervical lymph nodes (CLN), and blood also showed similar levels of macrochimerism. On the other hand, there were few GFP-positive cells in recipient BM and thymus (Thy); n = 4 to 5. (B) Fluorescent microscopic analysis of various organs in the recipients of WT intestine plus GFP-positive BM at day 120. Numerous GFP-positive cells were seen in graft MLNs and PPs as well as host spleen. Only few GFP-positive BM-derived cells were identified in recipient liver (Liv), heart (Ht), or BM. Blue indicates nuclear stain; 40×/0.75 NA oil-immersion objective was used. (C) Percentages of GFP-positive cells. GFP-positive positive cells were counted in the section and expressed as the percentage to the number of nucleus.