A: Trabeculae of spongy bone tissue
B: Red bone marrow
C: Osteoclasts . Nuclei are well defined. The darker spots inside the nuclei are the nucleoli. Note also the holes in the trabeculae where they have destroyed the bone matrix.
D: Osteoblasts,
E: Osteocytes (click in the bottom square, you will be able to see one of the osteocyte processes inside the matrix.