Question

Formation of cartilaginous bone involves:
a. Deposition of bony matter by osteoblasts and reabsorption by chondroclasts.
b. Deposition of bony matter by osteoblast only.
c. Deposition of bony matter and reabsorption by chondroblast.
d. None of the above

Answer 1

Hint: Cartilage bone is a hard and rigid form of connective tissues. These bones are elastic and rubber like which helps to cover and protect ends of long bones at the joints and nerves. These bones are structural components of the rib cage, the ear, the nose and intervertebral discs.

Complete answer:
Chondroblasts are the cells that help in cartilage formation while chondroblasts are cells that are involved in the loss of calcified cartilage. Bone formation or osteogenesis is a process that involves either intramembranous ossification or endochondral ossification. Intramembranous ossification is also called direct bone formation. Endochondral ossification is also called indirect bone formation.

For cartilaginous bone formation the mesenchyme or the embryonic connective tissue is first converted into cartilage. In the second step chondrocytes are formed. Next the chondrocytes form the bony framework and secrete the extracellular matrix. After this the chondrocytes become large in volume and help to add calcium carbonate to the matrix. Still later blood vessels enter the bony matrix. After this the chondroblasts die. Osteoclasts create hollow spaces that become the bone marrow. Later some osteoblasts derived from adjoining tissue begin bone formation on the degrading cartilage. Finally, the cartilage is replaced by bone. Example of cartilaginous bone: Rib cage, the ear, the nose, intervertebral discs and other parts of the body.

Hence, the correct answer is option (A).

Note: There are two types of cartilaginous joints which are primary and secondary cartilaginous joints. Primary cartilaginous joints are known as synchondrosis and are connected by hyaline cartilage. Secondary cartilaginous joints are called symphysis which includes fibrocartilaginous and hyaline joints which occur in midline.