Enter a clue or pattern or both:
The Clue
Embryonic membranes (7 letter answer)
The Answer
AMNIONS
Tags
Notes
The answer AMNIONS is so rare that it appears less than once every 2500 puzzles.
Definition
AMNION as a noun:
1. (amnion, amniotic sac, amnios) = thin innermost membranous sac enclosing the developing embryo of higher vertebrates (reptiles, birds and mammals)