In biology, an organ is a collection of tissues joined in a structural unit to serve a common function.
There is a "main" tissue, parenchyma, and "sporadic" tissues, stroma. The main tissue is the one that is unique for the specific organ. For example, the main tissue in the heart is the myocardium, while sporadic tissues include the nerves, blood and connective tissues. Functionally related organs often cooperate to form whole organ systems. Organs exist in all higher biological organisms, in particular they are not restricted to animals, but can also be identified in plants. In single-cell organisms like bacteria, the functional analogues of organs are called organelles.
A hollow organ is a visceral organ that is a hollow tube or pouch, such as the stomach or intestine, or that includes a cavity, like the heart or urinary bladder.
In biology, a hermaphrodite (Ancient Greek: ερμαφρόδιτος) is an organism that has reproductive organs normally associated with both male and female sexes.
Many taxonomic groups of animals (mostly invertebrates) do not have separate sexes. In these groups, hermaphroditism is a normal condition, enabling a form of sexual reproduction in which both partners can act as the "female" or "male". For example, the great majority of pulmonate snails, opisthobranch snails and slugs are hermaphrodites. Hermaphroditism is also found in some fish species and to a lesser degree in other vertebrates. Most plants are also hermaphrodites.
Historically, the term hermaphrodite has also been used to describe ambiguous genitalia and gonadal mosaicism in individuals of gonochoristic species, especially human beings. The word hermaphrodite entered the English lexicon in the late 14th century, derived from Greek Ερμαφρόδιτος Hermaphroditos, the son of the gods Hermes and Aphrodite in Greek mythology. The word intersex has come into preferred usage for humans, since the word hermaphrodite is considered to be misleading and stigmatizing, as well as "scientifically specious and clinically problematic".