Emergence of round-shaped cells from HF specimens. (A) A schematic representation of the HF. (B) Vibrissal follicles isolated from adult C57BL/6 mice were dissected into 3 fragments before culturing in the presence of 5 hematopoietic growth factors. Scale bar represents 500 μm. (C-D) Typical microscopic views of 3-week-old HF cultures are shown in 2 different magnifications. Scale bars represent 250 μm (C) and 50 μm (D). (E) Upper (•), intermediate (▴), and lower fragments (▪) of vibrissal follicles and peripheral blood samples (○) were cultured for 7 weeks under the same conditions and examined every week under phase-contrast microscopy for the emergence of round-shaped cells. The data indicate cumulative frequencies of the cultures showing apparent expansion of round-shaped cells (n = 50 for each source). Results shown in this figure are representative of 3 independent experiments.