Cartilage tissue consists of chondrocytes and cartilage matrix, cartilage tissue and its surrounding cartilage membrane constitutes cartilage, cartilage is divided into hyaline cartilage, elastic cartilage, and fibrocartilage according to the different cellulose components contained in the matrix. There are various methods for staining cartilage, such as toluidine blue method, Alisin blue method, saffron O method and so on.

The staining principle of bone tissue staining solution is that the basophilic cartilage combines with the basic dye Panax O to show red color, and the acidophilic bone combines with the acidic dye Panax O to show green or blue color, which contrasts sharply with the cartilage that shows red color, thus distinguishing the cartilage tissues from the bone tissues. Senna O is a cationic dye that binds multiple anions, and its display of cartilage is based on the binding of the cationic dye to the anionic groups in polysaccharides (chondroitin sulfate or keratan sulfate), and the coloring of Senna O is approximately proportional to the concentration of the anions, indirectly reflecting the content and distribution of the proteoglycans in the matrix; when the cartilage is damaged the glycoproteins in the cartilage will be released, resulting in an uneven distribution of the matrix components, thus When cartilage is damaged, the glycoproteins in cartilage will be released, resulting in uneven distribution of matrix components, thus leading to faint staining or no coloration of Senna O. The cartilage matrix stained with Senna O can be quantitatively analyzed by image analysis software. The acidic dye solid green binds to the eosinophilic components of the tissue to give it a green or blue color.