skeletal 2

What is ossification?

The process of bone formation.

When does ossification begin?

Around 8 weeks of embryonic development.

Before ossification, what are the embryo's supporting structures made of?

Fibrous connective tissue membranes and hyaline cartilage.

The embryonic supporting structures are shaped like what?

The bones they will become.

What type of tissue does intramembranous ossification begin with?

Fibrous connective tissue membrane (mesenchyme).

Which cells migrate to begin intramembranous ossification?

Mesenchymal cells.

During intramembranous ossification, mesenchymal cells differentiate into what?

Osteoblasts

during intramembranous ossification, what do osteoblasts secrete?

Osteoid

What is osteoid?

Unmineralized bone matrix.

During bone formation, when osteoblasts become trapped in osteoid, what do they become?

Osteocytes

What are the thin bony struts of spongy bone called?

Trabeculae

Which bones develop by intramembranous ossification?

Flat bones of the skull, mandible, and clavicle.

Endochondral ossification begins with what tissue?

Hyaline cartilage

Which cells migrate to begin endochondral ossification?

Mesenchymal cells.

During endochondral ossification, mesenchymal cells first differentiate into what?

Chondroblasts

During endochondral ossification, what attracts blood vessels to the cartilage model?

Death of the chondrocytes (after they enlarge and burst).

During endochondral ossification, osteoblasts form what around the diaphysis?

Bone collar

During endochondral ossification, what is the primary ossification center?

The first area where bone replaces cartilage in the diaphysis.

During endochondral ossification, where does the primary ossification center develop?

Diaphysis

During endochondral ossification, what develops in the epiphyses?

Secondary ossification centers

During endochondral ossification, where do secondary ossification centers develop?

Epiphyses

What do chondroblasts produce?

Hyaline cartilage.

During endochondral ossification, what happens to chondrocytes?

They enlarge (hypertrophy), then burst and die.

What is the primary ossification center?

The first area where bone replaces cartilage in the diaphysis.

At birth, what cartilage remains?

Articular cartilage and epiphyseal plate.

Intramembranous ossification starts with __________.

Fibrous membrane (mesenchyme).

Endochondral ossification starts with __________.

Hyaline cartilage.

Which ossification process forms most bones of the body?

Endochondral ossification.

Which ossification process forms flat bones of the skull?

Intramembranous ossification.