Amnion

4 clues
Embryonic sac
Membranous sac
Embryonic membrane
Protective membrane
Similar answers:
Abbreviation
Abbreviations
Abcletelevision
Abducktion
Abduction
Aberration
Aberrations
Abillionlives
Abjuration
Ablation
Ablution
Abolition
Abolitions
Abomination
Abortion
Aboutonebillion
Abovementioned
Abovesuspicion
Abrahamnebraska
Abrasion