Fluorescence microscopic picture of a femur longitudinal section showing the location of injected cells in the femur cavity.

Lin⁻ cells were labeled with carboxyfluorescein diacetate, succinimidyl ester (CFDA) and injected into a femur cavity by a 26-gauge needle. The needle insertion hole was sealed with bone wax. The mouse was killed 5 minutes after injection, and the injected femur was removed for fluorescence microscopic analysis. Original magnification, 2 × 20.