Bone Development - 10/01/2015

Question 1

Osteogenesis (ossification)

Answer 1

Bone tissue formation.

Question 2

Stages

Answer 2

• Bone formation- begins in the 2nd month of development
• Postnatal bone growth-until early adulthood
• Bone remodeling and repair - lifelong

Question 3

Two Types of Ossification

Answer 3

1. Intramembranous ossification
mesenchyme-->Bone
-(embryonic tissue)
-Skull and clavicles
2. Endochondrial ossification
mesenchyme--->hyaline cartilage--->Bone
-most of the rest of the skeleton

Question 4

Steps of Intramembranous ossification

Answer 4

1. Ossification center (osteod&osteoblasts appear in fibrous connective tissue.
2. Bone matrix (osteoid) is secreted within the fibrous membrane and calcifies.
   - Osteoid calcifies from mother’s diet.
   - Spicules forming.
3. Woven Bone and periosteum form
   - spicules formed together= spongy bone
   - mesenchyme compressed and forms into periosteum
4. Compact bone replaces spongy bone, just deep in periosteum. Red bone marrow appears.

Question 5

Steps of Endochondrial ossification

Answer 5

1. Bone collars forms and hyaline cartilage model (week 9)
2. Cartilage in the center of the diaphysis calcifies and then develops cavities.
   - Cavitation—> removals of hyaline cartilage (death of chondrocyte)
   - Proliferation=mitosis
   - Hypertrophy=enlarge
   - Calcification=hardens
3. Primary Ossification Center (3 month)
   - blood vessels invading empty cavities (areolar CT, osteoblasts and osteoclasts)
4. Completion of Primary ossification center and beginning secondary ossification center (proximal and distal epiphysis) (Birth)
5. Secondary Ossification completes and hyaline cartilage remains in the epyphyseal line and joints of the bone. (Childhood to Adolescence).