Question

Thalidomide was a morning sickness drug given to pregnant people; it caused babies to be born without arm bones. If recent studies have shown that thalidomide prevents the formation of new blood vessels, describe the type of bone development inhibited by the drug and what stage of ossification was affected.

a) Long bone development; intramembranous ossification
b) Axial bone development; endochondral ossification
c) Appendicular bone development; intramembranous ossification
d) Axial bone development; intramembranous ossification

Answer 1

Thalidomide inhibited appendicular bone development by impeding endochondral ossification, essential for long bone formation in the limbs, due to its anti-angiogenic effects.

Step-by-step explanation:

Thalidomide, which was used to prevent morning sickness, profoundly affected appendicular bone development in the developing fetus by inhibiting the formation of new blood vessels, a process essential for proper bone growth. The affected stage of ossification was endochondral ossification, the method through which long bones in the limbs are formed. During this process, a cartilage template is gradually replaced by bone; however, the inhibition of angiogenesis prevented the normal maturation and growth of these bones, leading to limb abnormalities.