Mammal
- chorion
The outermost membranous sac enclosing the embryo in higher vertebrates (reptiles, birds...
- amnion
Thin innermost membranous sac enclosing the developing embryo of higher vertebrates (reptiles,...
Also contains
- pocket
(anatomy) saclike structure in any of various animals (as a marsupial or gopher or pelic...
- vesicle
A small anatomically normal sac or bladderlike structure (especially one containing flu...
- bladder
A distensible membranous sac (usually containing liquid or gas).
- air sac
A tiny sac for holding air in the lungs; formed by the terminal dilation of tiny air pa...
- saccule
A small sac or pouch (especially the smaller chamber of the membranous labyrinth).
- air bladder
An air-filled sac near the spinal column in many fishes that helps maintain buoyanc...
- coelenteron
The saclike body cavity of a coelenterate.
- air sac
Any of the membranous air-filled extensions of the lungs of birds.
- air sac
Any of the thin-walled extensions of the tracheae of insects.
- yolk sac
Membranous structure enclosing the yolk of eggs in birds, reptiles, marsupials, and some...
- yolk sac
Membranous structure that functions as the circulatory system in mammalian embryos until...
- acinus
One of the small sacs or saclike dilations in a compound gland.
- bursa
A small fluid-filled sac located between movable parts of the body especially at joints.
- pericardial sac
The membrane surrounding the heart.
- cistern
A sac or cavity containing fluid especially lymph or cerebrospinal fluid.