Flat bones, like the skull or jaw bone develop from clusters of condensed mesenchyme. A developing fetal skull is shown in the above photo. Areas of condensed mesenchyme lie around the shelves and spicules of bone. Look for these areas in your slide 23.  The following photos show spicules of developing bone from this slide. Find osteoblasts, osteocytes, and condensed mesenchyme.  Also, can you find osteoclasts?