Tha baby lives inside a transparent membrane called the amniotic sac. The sac is filled with a salty solution which bathes the body's cells. In a complex process - the body recycles the fluid, swallowing some, absorbing some, expelling some - while at the same time manusacturing most of it. The embryo floats almost weightlessly in the fluid so it is protected from shocks and does not have to fight gravity..
