Organ

The unit of body structure, composed of various tissues and performing specific functions. Organs can be: analogous – different in origin, but have similar structures, as they perform similar functions (e.g., bat and bird wings); homologous – they have the same origin, but perform different functions, e.g., human hand, dog limb, whale’s flipper, bat wing; rudimentary – lost their functions, but still present in adult animals; usually they remain as vestiges (e.g., remnants of human ear muscles, third eyelid, coccyx, etc.); provisional – temporary organs that maintain the connection between the embryo and the environment, e.g., yolk sac, placenta.

Source | Glossary of Most Commonly Used Biomedical Terms and Concepts | Lithuanian University of Health Sciences | Academician Professor Antanas Praškevičius, Professor Laima Ivanovienė