<Tr> <Th> FMA </Th> <Td> 67498 </Td> </Tr> <Tr> <Td_colspan="2"> Anatomical terminology (edit on Wikidata) </Td> </Tr> <P> Organs are collections of tissues with a similar function . Plant and animal life relies on many organs that coexist in organ systems . </P> <P> Organs are composed of main tissue, parenchyma, and "sporadic" tissues, stroma . The main tissue is that which is unique for the specific organ, such as the myocardium, the main tissue of the heart, while sporadic tissues include the nerves, blood vessels, and connective tissues . The main tissues that make up an organ tend to have common embryologic origins, such as arising from the same germ layer . Functionally related organs often cooperate to form whole organ systems . Organs exist in all organisms . In single - celled organisms such as bacteria the functional analogue of an organ is known as an organelle . In plants there are three main organs . </P>

What is the definition of a human organ