Three dimensional ultrastructure of transverse (Harris) lines in the long bone.

To investigate the occurrence of transverse lines in long bones of adults, we studied 27 cadavers (14 males and 13 females). After confirming the presence of a transverse line, a cross-sectional sample was examined macroscopically, and by soft X-ray and scanning electron microscopy. The following results were obtained: 1. According to roentgenograms, transverse (Harris') lines were observed in 40.7% of the distal half of the femur and in 29.6% of the proximal half of the tibia. 2. Macroscopic examination of the bone cross-sections at the level of the transverse line showed various membranous structures. 3. In scanning electron micrographs, no marked difference in structure was observed between the transverse line trabeculae and the compact bone.