gyre
The rising and sinking motion is called convection current.
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.
Choroid Plexus
pituitary system
the answer is mucus
The part of the diencephalon that forms cerebrospinal fluid is called the choroid plexus. It is responsible for producing the majority of the cerebrospinal fluid found within the central nervous system.
epideynal cells
a surface current forms
Alternating Current (AC) and Direct Current (DC)
convection currents
choroid plexus
At the bottom of a substance, part of it is heated by something. This causes it to rise above the rest. However, it soon cools and drops back down again where it is then heated, etcetera. This forms a constant current of part of the substance rising then dropping and repeating.