Lamellae

Lamellae are the thin, sheet-like layers that make up mature bone, a bit like the rings you see in a tree trunk. In compact (cortical) bone, these layers wrap in concentric circles around a tiny central canal, forming a unit called an osteon. In spongy (trabecular) bone, lamellae stack more like layers in plywood.

Each lamella is built from collagen fibers laid down in a specific direction, with the fiber direction shifting slightly from one layer to the next. This alternating pattern, combined with mineral crystals packed into the collagen, is what gives healthy bone both strength and some flexibility, so it can resist breaking under everyday stress and impact.

This organized, layered structure is different from the messier, fast-made 'woven bone' the body uses for quick repairs, like right after a fracture. Over time, woven bone is replaced by true lamellar bone through normal bone remodeling. Some osteoporosis medications work by stimulating new bone formation, but how that new bone's structure compares to normal lamellar bone is a detailed, evolving area of research. Any questions about how a specific medication works should be directed to your doctor.