Osteogenesis and Bone Growth

Question 1

What are the four types of bone cells?

Answer 1

Osteoprogenitor cells
Osteoblasts
Osteocytes
Osteoclasts

Question 2

What is osteogenesis?

Answer 2

Bone formation

Question 3

What are the types of ossification?

Answer 3

Intramembranous ossification: Formation of bone directly from fibrous connective tissue
Endochondral ossification: Formation of bone from hyaline cartilage models

Question 4

When does intramembranous ossification begin?

Answer 4

begins in utero during fetal development, continues until adolescence

Question 5

How do skull and shoulders deform during passage through the birth canal?

Answer 5

At birth, skull and clavicles are not fully ossified, sutures of the skull are not closed. This allows skull and shoulders to deform.

Question 6

Which are the last bones to be ossified via intramembranous ossification?

Answer 6

Flat bones of the face, they reach their adult size at the end of adolescent growth

Question 7

From where do the compact and spongy bone develop during intramembranous ossification?

Answer 7

Sheets of mesenchymal connective tissue

Question 8

Which bones are are formed via intramembranous ossification?

Answer 8

Flat bones of the face, most cranial bones, clavicles (collarbones)

Question 9

What is an ossification center?

Answer 9

Early osteoblasts appear in a cluster called ossification center which will ultimately spread out due to the formation of bone tissue.

Question 10

Explain the process of intramembranous ossification.

Answer 10

-The process begins when mesenchymal cells differentiate into specialized cells. Some cells form capillaries, while others develop into osteogenic cells and then osteoblasts. These osteoblasts appear in a cluster of cells called ossification center. -Osteoblasts secrets osteoid (uncalcified matrix) which calcifies as mineral salts are deposited on it, thereby entrapping the osteoblasts within it.
-Once entrapped, osteoblasts become osteocytes. As osteoblasts transform into osteocytes, osteogenic cells in surrounding connective tissue differentiate into new osteoblasts.
-Trabecular matrix is formed, osteoblasts on the surface of the spongy bones becomes the periosteum.
-Compact bones develops superficial to trabecular bone, crowded blood vessels develop into red marrow