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 pres ence of a transverse line, a cross-sectional sample was examined macroscopi cally, and by soft X-ray and scanning electron microscopy. The following re sults were obtained: 1. According to roentgenograms, transverse (Harris') l ines 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 cro ss-sections at the level of the transverse line showed various membranous s tructures. 3. In scanning electron micrographs, no marked difference in str ucture was observed between the transverse line trabeculae and the compact bone.