A: Trabeculae of spongy bone tissue
B: Red bone marrow
C: Endosteum made mostly of osteoblasts
1: osteocytes
2: Osteoblasts,
3: Osteoclast
At the location indicated by the arrow and the question mark, an osteoclast destroy the bone matrix. You can see a big indentation in the trabeculae indicative of bone resorption.