Final answer:
Fetal lungs are filled with amniotic fluid which helps in their development.
Step-by-step explanation:
The fetal lungs are filled with amniotic fluid. Amniotic fluid is a clear, slightly yellowish liquid that surrounds and protects the developing fetus in the womb. It is produced by the fetus's urine and by secretions from the lungs and other fetal structures. The amniotic fluid plays a crucial role in the development of the lungs, as it helps them to expand and grow properly.
Learn more about Fetal lung development