Endochondral Ossification

Question 1

Describe Step 1

Answer 1

1) Embryo skeleton is hyaline cartilage until around 5 weeks

Question 2

Describe Step 2

Answer 2

2) Collar of periosteal bone appears in the shaft (embryo 6-8 weeks)

Question 3

Describe Step 3

Answer 3

3) Central cartilage calcifies. Nutrient artery penetrates, supplying bone-depositing osteogenic cells. Primary ossification centre formed. (foetus 8-12 weeks)

Question 4

Describe Step 4

Answer 4

4) Medulla becomes cancellous bone. Cartilage forms epiphyseal growth plates. Epiphyses develop secondary centres of ossification. (postnatal)

Question 5

Describe Step 5

Answer 5

5) Epiphyses ossify and growth plates continue to move apart, lengthening bone. (prepubertal)

Question 6

Describe Step 6

Answer 6

6) Epiphyseal growth plates replaced by bone. Hyaline articular cartilage persists. (mature adult)