Compléter ORGANSVersion en ligne Complete par Dante Aguilar Tormo 1 organ organs organisms organ heart sporadic restricted analogue same tissue organisms myocardium tissue organelle systems nerves origins to plants vessels The organs are composed of main tissue , parenchyma , and " " tissues , stroma . The main is that wich is unique for the specific , such as , the , the main of the , while sporadic tissues include the , blood , and connective tissues . The main tissues that make up an tend to have common embryologic , such as arising from the germ layer . Functionally related often cooperate form whole organ . Organs exist in all higher biological , in particular they are not to animals , but can also be identified in . In single - cell like bacteria , the functional of an organ is called .