True coelom originates from mesoderm and is lined by epithelial cells of mesodermal origin.
The coelom is one of the characteristic features of metazoans. The true coelom is a body cavity formed during embryo development from the three germinal layers. The coelom is lined by mesodermal epithelium cells. The presence or absence of coelom is one of the criteria for classifying animals.
- Coelom works as a shock absorber and protects from any mechanical shock. It gives more flexibility to the body organs to move and protects from any damage on minor bends by cushioning the internal organs.
- The coelomocyte cells that either float freely in the coelom or attached to the wall support the immune system. They support the immune system by initiating a humoral immune response and phagocytosis.
- Coelom gives the extra space required by organs to develop and function.
There are three structural types of body plans related to the coelom.
- Acoelomates (animals with no coelom)
- Pseudocoelomates (animals with false coelom)
- Eucoelomates (animals with true coelom)