Which description matches early fracture healing in the sample?

• A. Thick unorganized tumor bone trabeculae with numerous mitoses and no single osteoblast layer
• B. Trabeculae of woven bone lined by a single layer of osteoblasts; space between trabeculae filled by loose mesenchymal cells with capillaries and hemorrhage
• C. Periosteal new bone without endosteal involvement
• D. Chondroid proliferation with low cellularity

Answer: (B)

In the earliest phase of fracture healing, you see a rapid formation of woven bone that creates a provisional scaffold across the fracture. This woven bone appears as trabeculae that are lined by a single layer of osteoblasts, signaling active bone formation. The spaces between these trabeculae are filled with loose mesenchymal tissue, capillaries, and hemorrhage as the fracture channel is organized and revascularized. This combination—woven bone trabeculae with osteoblasts and a vascular, cellular, hemorrhagic inter-trabecular space—is characteristic of the initial callus forming across the fracture.

The other descriptions point to processes not typical of the early fracture-phase: a thick, unorganized “tumor-like” bone with high mitotic activity suggests neoplastic bone formation rather than normal healing; periosteal new bone without endosteal involvement misses the endosteal component and the woven bone formation across the fracture; and chondroid proliferation with low cellularity reflects cartilaginous (endochondral) tissue that appears later in healing rather than the initial woven bone stage.