Out of 218 cadavera for autopsy, 16 (7.30%) defective neural arches of the 5th lumbar vertebra were found, of which 12 neural arches in 6 cadavera were examined histologically with serial sections.
The results obtained were mainly as follows:
1. In osseous parts of the defective neural arches, it was found that bone trabeculae were scanty and atrophied, bone marrows were enlarged and changed in fibrosis and Havers's canals were also enlarged. Lacunar resorption was seen in the bone trabeculae near the defected area which was bordered with calcified plate.
2. The defected areas were occupied by connective tissues and fibrous cartilages mixed with hyaline cartilages. In peripheral part of the defected areas, proliferation and scaring of the connective tissues were seen, and in central part of them, fissures and vesicular degeneration were prevalent. Isolated bone particles, calcified tissues and cartilage islands were seen in some of the defected areas.
3. Inferior articular cartilage of the defective vertebrae was noticed to be more degenerated than superior articular cartilage.
