Three-dimensional architecture and development of lumber intervertebral discs.

Area of Science:

• Biomedical Engineering
• Anatomy
• Developmental Biology

Background:

• The human lumbar intervertebral disc (IVD) is a complex structure critical for spinal function.
• Understanding the collagenous architecture of the IVD, particularly its interface with vertebral bodies, is essential for diagnosing and treating spinal pathologies.

Purpose of the Study:

• To elucidate the three-dimensional collagenous architecture of human lumbar intervertebral discs.
• To investigate the fibrillar interconnections between the intervertebral disc and adjacent vertebral bodies.

Main Methods:

• Scanning electron microscopy (SEM) was employed to visualize the microarchitecture.
• Polarized light microscopy (PLM) was utilized to study the fibrillar orientation and organization.

Main Results:

• The annulus fibrosus and cartilage end-plates form a closed-pack system around the nucleus pulposus in adults.
• Fibrillar connections to vertebral bodies are established by the tenth embryonic month, with thinner fibrils in fetuses compared to adults.
• The inner annulus fibrosus connects to the cartilage end-plate, while the outer annulus fibrosus anchors firmly into the vertebral bodies.

Conclusions:

• A distinct fibrillar anchoring system connects the intervertebral disc to vertebral bodies, present even in the full-term fetus.
• The development of this closed-pack system is a critical aspect of spinal development.