Final answer:
Type 1 intramembranous bone develops from mesenchymal tissue via intramembranous ossification, forming flat bones like the skull, mandible, and clavicles. Mesenchymal cells differentiate into osteoblasts which create spongy bone that's remodeled into compact bone.
Step-by-step explanation:
Type 1 intramembranous bone refers to a classification of bone that develops directly from sheets of mesenchymal connective tissue through a process known as intramembranous ossification. This process includes the formation of flat bones such as those in the skull, the mandible (jawbone), and the clavicles (collarbones). During intramembranous ossification, mesenchymal cells congregate in areas called ossification centers, differentiate into osteoblasts, and start secreting the osteoid. This eventually leads to the formation of spongy bone, which is then remodeled into a layer of compact bone, with areas of spongy bone often being filled with red bone marrow.