Observe the scaffolding of bony trabeculae in the flat bones (i) surrounding the nasal cavity of a very young puppy. At this stage of development the bone is referred to as CANCELLOUS or SPONGY BONE.
As the puppy matures the spaces will be filled in by new layers of bone and osseous tissue will predominate rather than connective tissue filled spaces. When this occurs the one is said to be COMPACT and DENSE BONE. In the next PS take a look at one of the spaces, which is magnified, and attempt to visualize how the space is filled in to form compact bone.
The letter "h" is on hyaline cartilage and the arrowhead is on CT between spongy bone and hyaline cartilage. THE CT COMPRISES THE PERIOSTEUM ON ONE SIDE AND PERICHONDRIUM ON THE OTHER.