Structural differences between immature and mature articular cartilage of rabbits by microscopic MRI and polarized light microscopy

This study aimed to determine the structural features between immature and mature articular cartilage from the humeral and femoral joints of rabbits. Specimens of articular cartilage (n = 6 for immature tissue, n = 6 for mature tissue) that were still attached to the underlying bone from a humerus (shoulder joint) or femur (knee joint) were imaged using microscopic MRI (mu MRI) and polarized light microscopy (PLM). Quantitative mu MRI data with a pixel resolution of 11.7-13.2 mu m revealed a number of differences between the immature and mature cartilage, including total thickness, and T2 and T1 rho relaxation values. Quantitative PLM data with a pixel resolution of 0.25-1 mu m confirmed the mu MRI results and revealed additional differences in cellular features between the tissues. The mature cartilage had a clearly defined tidemark, which was absent in the immature tissue. The ability to differentiate specific maturation-related cartilage characteristics could be beneficial to translational studies of degenerative diseases such as osteoarthritis.

Automated summary

This study compared the structural and cellular features between immature and mature articular cartilage using microscopic MRI and polarized light microscopy. The results revealed differences in thickness and relaxation values, as well as the presence of a tidemark in mature cartilage. These findings are important for studying degenerative diseases such as osteoarthritis.