Metaphysis, which is an anatomy term, means "the narrow part of the long bones between the epiphysis and the diaphysis". It is a term related to bone formation. The metaphysis encompasses a developing plate, this portion of bone that develops during childhood and ossifies near the diaphysis and epiphysis as it develops.

The metaphysis can be anatomically divided into three main parts according to their tissue contents: the epiphyseal plate, which is a cartilaginous tissue, the metaphysis, which is bone tissue, and the fibrous tissue surrounding the outer surface of the plate. 

Developed during childhood, plaque contains connective cartilage tissue to enable bone to develop. In adulthood (between 18-25 years), the content of the plaque, which has developed, stops its development and ossifies completely, becoming a single bone. In an adult, the metaphysis functions to transfer the load from the articular surface to the diaphysis, which bears the weight.

The epiphysis is the rounded ends of long bones. In the joint part, the epiphysis is surrounded by the articular cartilage, and under this covering, there is a region similar to the epiphyseal plate, and this region is called the subchondral bone. The pineal is filled with red bone marrow, which produces erythrocytes, or red blood cells.

The diaphysis is the main part of the long bones in the middle. The diaphysis is made of cortical bone and contains bone marrow and adipose tissue. It contains both red and yellow bone marrow. The main ossification takes place in the diaphysis.