The pseudocoelom, a bodily cavity of pseudocoelomate metazoans, is filled with fluid and lacks a cellular peritoneal lining, unlike a real coelom.
Most pseudocoelomates (such as those in the groups Nematoda and Rotifera) are diminutive, and none have separate vascular systems.
A bodily cavity that is partially enclosed by mesodermal tissue because it is located between mesodermal and endodermal tissue is known as a pseudocoelom.
Because mesodermal tissue entirely encircles a "real" coelom, it can be separated into compartments.
The Aschelminthes phylum contains pseudocoelom, also known as a pseudo coelom. Mesoderm does not line with the pseudocoelom.
Between the ectoderm and the endoderm are sporadic pouches of mesoderm.