Used in histology to stain cartilage tissues, Safranine O highlights proteoglycans in the extracellular matrix, making cartilage visible under the microscope. It is commonly applied in joint and bone tissue studies, especially in research on arthritis and cartilage degeneration. The red or pink color contrast helps distinguish cartilage from other tissue types when used in combination with counterstains like Fast Green or Light Green. It is also used in spine and growth plate evaluations in developmental biology.