Embrology

Question 1

Outline the difference between the two main types of ossification in the developing
embryo, including giving an example of where each process occurs. (6 marks)

Answer 1

Answer:
Endochondral Ossification - Most of the bony skeleton forms by this process, that replaces a
developmental cartilage template with bone. Axial skeleton, limbs, long bones, base of
skull. (3 marks)
Intramembranous Ossification - Only specific parts of the skeleton form by this process,
where bone forms by direct ossification of mesenchyme without a pre-existing cartilage
template. This process occurs in regions of the skull (flat bones of neurocranium) and the
clavicle. (3 marks)