Epiphysis

An epiphysis (from Ancient Greek ἐπί (epí) 'on top of', and φύσις (phúsis) 'growth'; pl.: epiphyses) is one of the rounded ends or tips of a long bone that ossify from a secondary center of ossification. Between the epiphysis and diaphysis (the long midsection of the long bone) lies the metaphysis, including the epiphyseal plate (growth plate). At the joint, the epiphysis is covered with articular cartilage; below that covering is a zone similar to the epiphyseal plate, known as subchondral bone. In evolution, reptiles do not have epiphyses and diaphyses, being restricted to mammals.

The epiphysis is filled with red bone marrow, which produces erythrocytes (red blood cells).