Intrafollicular emergence of bone marrow–derived leukocytes. (A) Vibrissal follicles isolated from the chimeric mice reconstituted with EGFP⁺ bone marrow cells were cultured for 3 weeks in the presence of 5 added growth factors and examined under confocal microscopy. The displayed images represent multiple clusters of EGFP⁺ cells detected in 2 different planes within the same HF sample (left and middle panels) and extrafollicular expansion of EGFP⁺ cells on the top of EGFP^– fibroblasts observed on the plane corresponding to the surface of culture plates (right panel). (B) Vibrissal follicles freshly isolated from the chimeric mice reconstituted with EGFP⁺ bone marrow cells were examined under confocal microscopy. The images show 3 vertical planes (with the follicular papilla side at the bottom) of a representative HF sample scanned sequentially with 5 μm distance between planes. The ORS regions delineated by their faint autofluorescence signals are outlined by dotted lines. Data shown are representative of 3 (A) or 2 (B) independent experiments. Scale bars represent 50 μm (A) or 100 μm (B).