Intramembranous Ossification

Question 1

Step 1

Answer 1

Mesenchyme becomes highly vascularized, and mesenchymal cells aggregate, enlarge, and differentiate into osteoblasts. The osteoblasts then cluster together and start to secrete the organic components of the matrix. The resulting osteoid then becomes mineralized through the crystallization of calcium salts.

Question 2

Step 2

Answer 2

As ossification proceeds, the osteoblasts that become surrounded by osteoid differentiate into osteocytes. These cells will remian trapped within tiny spaces known as lacunae. The developing bone grows outward from the ossification center into small struts called spicules. Although osteoblasts are still being trapped in the expanding bone, mesenchyme cell divisions continue to produce additional osteoblasts.

Question 3

Step 3

Answer 3

Bone growth is an active process, and osteoblasts require oxygen and a reliable supply of nutrients. As blood vessels branch within the region and grow between spicules, the rate of bone growth accelerates. As spicules interconnect, they trap blood vessels within the bone.

Question 4

Step 4

Answer 4

continued deposition of bone by osteoblasts creates a bony plate that is perforated by blood vessels. As adjacent plates fuse together, the bone structure becomes increasingly complex.