A
hemocoel is a cavity or series of spaces between the organs of organisms with
open circulatory systems, like most
arthropods and
mollusks. A combination of
blood,
lymph, and
interstitial fluid called
hemolymph circulates through the hemocoel.
The term is also used to describe the space in the connective tissue compartment derived from the embryonic blastocoel with contributions from mesoderm, filled with blood.