Chapter 32, Problem 13STP

Summary Introduction

To write:

Development of fetal cartilages into the bone.

Introduction:

Bone and cartilages are types of connective tissue. The Skeleton system of the human body is made up of bones of different shapes and sizes. Long bones are present in arms and legs. Wrist bones are short bones. Skull is made up of flat bones. Vertebrae and facial bones are irregular bones.

Explanation of Solution

In the embryo stage, the skeleton is composed of cartilages. In the fetal stage, cells present in the cartilages of the fetus develop into osteoblasts. Osteoblasts form the bone in the human body. The process of formation of bone from osteoblasts is known as ossification. All the cartilages in the fetal stage develop into bones except the cartilages present at the tip of the nose, pinna of the ear, intervertebral discs and on the lining of movable joints. Growth and repair of bones are also done by the osteoblasts. The replacement of old cells with new cells in bones is known as the remodeling of bones. Remodeling of bones occurs throughout life. Osteoclasts are the cells that breakdown bone cells.

Conclusion

Fetal cartilages develop into bones by the development of cells in fetal cartilages into osteoblasts which is a bone-forming cell.