There are two types of ossification centers - primary and secondary.

A primary ossification center is the first area of a bone to start ossifying.

Most bones have more than one secondary ossification center.

In the patella an ossification centre develops between the ages 3-6 years.

In the calcaneus, an ossification center is developed during the 4-7th week of fetal development.

During the 7-8th intrauterine month an ossification center is formed in the talus.

Bones are connected by hyaline cartilage and sometimes occur between ossification centers.

Examples in humans are the "growth plates" between ossification centers in long bones.

The point of union of the primary and secondary ossification centers is called the epiphyseal line.

After eleven weeks an accessory ossification center develops into the alar region of the premaxilla.

About the time of birth, a secondary ossification center appears in each end (epiphysis) of long bones.

These fractures occur at apophyses (bony projections that lack secondary ossification centers).

Endochondral ossification begins with points in the cartilage called "primary ossification centers."

Previously, bipartite patellas were explained as the failure of several ossification centres to fuse, but this idea has been rejected.

Next, the chondrocytes cease to divide and begin to hypertrophy (enlarge), much like they do in the primary ossification center of the fetus.

The blood vessels stimulate a primary ossification center to grow - this is the place where bone tissue will begin to take the place of cartilage.

UAP is caused by a separation from the ulna of the ossification center of the anconeal process.

The cancellous bone forms via two ossification centres, one medial and one lateral, which fuse later on.

NOTE: most other bones (e.g. vertebrae) also have primary ossification centres and bone is laid down in a similar manner.

The acromion has four ossification centers called (from tip to base) pre-acromion, meso-acromion, meta-acromion, and basi-acromion.

Periosteal buds carry mesenchyme and blood vessels in and the process is similar to that occurring in a primary ossification center.

Median maxillary dysplasia is caused by a development failure of the medial part of the maxillary ossification centers.

He is credited with describing "Kerckring's ossicles", which is an occasional ossification centre in the occipital bone that appears around the 16th week of gestation.

Secondary ossification centers develop to form bone, although unlike with the primary ossification center, spongy bone stays at the center of epiphyses instead of marrow.

The first ossification centers in the area of the future premaxilla appear during the seventh week above the germ of the second incisor on the outer surface of the nasal capsule.

In the patella an ossification centre develops between the ages 3-6 years.

He is credited with describing "Kerckring's ossicles", which is an occasional ossification centre in the occipital bone that appears around the 16th week of gestation.