Final answer:
The tidemark is seen separating the superficial zone and the deep zone in a cross-section of articular cartilage. It marks the boundary between the calcified and non-calcified regions. The tidemark is important for providing support and shock absorption in the joint.
Step-by-step explanation:
In a cross-section of articular cartilage, the tidemark is seen separating the superficial zone and the deep zone. The superficial zone is located towards the surface of the articular cartilage, while the deep zone is closer to the bone. The tidemark itself is a thin line that separates the calcified cartilage and the non-calcified cartilage. It marks the boundary between the two regions. For example, in the articular cartilage of the femur and tibia in the knee joint, the tidemark separates the superficial zone that experiences friction and wears down over time, from the deeper zone that provides support and shock absorption.
In contrast, the deep zone has more rounded chondrocytes and collagen fibers arranged perpendicularly, which helps the tissue withstand compressive forces. These two regions together play a critical role in reducing friction and acting as a shock absorber in joint movements, such as those of the long bones that are coated with hyaline cartilage at their articulating ends.