There is no such thing as an "ovarian sac".
The amnion is a membrane building the "amniotic sac" that surrounds and protects an embryo.
Ovary
The Amnion or the Amniotic Sac
The inner cell mass (ICM) produces three embryonic membranes, the amnion, allantois, and the yolk sac.
The ovarian sac is also known as the follicle.
The embryonic sac, or amniotic sac, is composed of a membrane called the amnion. The amnion serves to protect the embryo by providing a physical barrier against external threats and a cushioned environment for development. Additionally, the amnion secretes amniotic fluid which helps to regulate temperature, provide buoyancy, and prevent desiccation of the embryo.
The extraembryonic membrane that forms a fluid-filled sac is the amnion. It helps protect and cushion the developing embryo by surrounding it with amniotic fluid.
The inner most membrane is the fluid filled amniotic sac, next is the yolk sac, where the first blood cell originates. The allantois forms near the yolk sac, while the chorion surrounds all the other ones.
A fluid-filled sac that surrounds an embryo is called an amniotic sac. This sac contains amniotic fluid, which provides protection and cushioning for the developing embryo.
the amnion is a fluid-filled sac that will protect the embryo from mechanical shock.
Amnion. It starts out as the Second Layer of cells in the Zygote/Fert Egg.
Ovarian follicle
Amnion is the membrane that covers the embryo. Chorion is the membrane that covers the amnion, the yolk sac, and the allantois. The space delimited by the chorion and the amnion is called amniotic cavity and it is filled with aminiotic fluid. The amniotic cavity has the functions of preventing desiccation of the embryo and of protecting it against mechanical shocks.