secondary ossification

Examples of secondary ossification in the following topics:

• Postnatal Bone Growth

  • Secondary ossification occurs after birth at the epiphyses of long bones and continues until skeletal maturity.
  • Secondary ossification occurs after birth.
  • During postnatal bone formation, endochondral ossification initiates bone deposition by first generating a structural framework at the ends of long bones, within which the osteoblasts can synthesize a new bone matrix.
  • Zone of bone deposition (ossification): The walls between the lacunae break down and the chondrocytes die.
  • Differentiate among the zones of development from cartilage to bone in postnatal ossification

• Stages of Bone Development

  • Although bone initially forms during fetal development, it undergoes secondary ossification after birth and is remodeled throughout life.
  • The formation of bone during the fetal stage of development occurs by two processes: intramembranous ossification and endochondral ossification.
  • The steps in intramembranous ossification are:
  • Endochondral ossification begins with points in the cartilage called "primary ossification centers."
  • Secondary ossification occurs after birth and forms the epiphyses of long bones and the extremities of irregular and flat bones.

• Bone Development

  • Intramembranous ossification stems from fibrous membranes in flat bones, while endochondral ossification stems from long bone cartilage.
  • The development of bone from fibrous membranes is called intramembranous ossification; development from hyaline cartilage is called endochondral ossification.
  • They then differentiate into osteoblasts at the ossification center.
  • Endochondral ossification is the process of bone development from hyaline cartilage.
  • Secondary ossification centers form in the epiphyses as blood vessels and osteoblasts enter these areas and convert hyaline cartilage into spongy bone.

• Development of the Skeleton

  • Early in gestation, a fetus has a cartilaginous skeleton that becomes bone in the gradual process of endochondral ossification.
  • Early in gestation, a fetus has a cartilaginous skeleton from which the long bones and most other bones gradually form throughout development and for years after birth in a process called endochondral ossification.
  • Intramembranous ossification is the direct laying of bone into the primitive connective tissue (mesenchyme).
  • Endochondral ossification involves cartilage as a precursor.
  • Chondrocytes in the primary center of ossification begin to grow (hypertrophy).

• Growth of Bone

  • It is a layer of hyaline cartilage where ossification occurs in immature bones.
  • The newly-deposited bone tissue at the top of the zone of ossification is called the primary spongiosa.
  • The older bone at the bottom of the zone of ossification is called the secondary spongiosa.
  • The bottom-most row is the zone of ossification which is part of the metaphysis.
  • The newly-deposited bone tissue at the top of the zone of ossification is called the primary spongiosa, while the older bone is labeled the secondary spongiosa.

• Embryonic and Fetal Bone Formation

  • During fetal development, bone tissue is created through intramembranous ossification and endochondral ossification.
  • The skull and vertebral column are produced by intramembranous ossification.
  • Unlike the other process of bone creation— endochondral ossification—intramembranous ossification does not involve cartilage.
  • Unlike intramembranous ossification, cartilage is present during endochondral ossification.
  • The first site of ossification occurs in the primary center of ossification, which is in the middle of diaphysis (shaft).

• Primary and Secondary Research

• Secondary Groups

  • Some secondary groups may last for many years, though most are short term.
  • Secondary relationships involve weak emotional ties and little personal knowledge of one another.
  • The distinction between primary and secondary groups was originally proposed by Charles Cooley.
  • A secondary group is one you have chosen to be a part of.
  • Primary groups can form within secondary groups as relationships become more personal and close.

• Fontanels

  • The ossification of the bones of the skull causes the fontanelles to close over a period of 18 to 24 months; they eventually form the sutures of the neurocranium.
  • This is called intramembranous ossification.

• Primary and Secondary Groups

  • Secondary groups are large groups whose relationships are impersonal and goal-oriented.
  • Some secondary groups may last for many years, though most are short term.
  • People in a secondary group interact on a less personal level than in a primary group.
  • Since secondary groups are established to perform functions, people's roles are more interchangeable.
  • Examples of secondary groups include: classmates in a college course, athletic teams, and co-workers.