This slide shows a section of red bone marrow within cancellous (spongy) bone.  Note the trabecula (ridge) of bone on the left side of the image.  Osteocytes (bone cells) can be seen within spaces in the bone called lacunae.  Adjacent to the trabecula are bone-forming cells called osteoblasts.  Once again, note the adipose cells and  giant megakaryocytes that break down to form blood-clotting elements called platelets.