Atresia refers to a situation where there is underdevelopment of a structure with very rudimentary remnant tissues. This contrasts with an agenesis meaning there is no development of the structure as all. The term atresia is often used with hollow structures such as a bronchus or intestine.
- respiratory tract
- alimentary tract
- bile ducts
- genito-urinary tract
Some authors occassionally overlap the two terms (i.e atresia and agenesis).