2.💗DEVELOPMENT AND GROWTH OF BONES. HISTOGENESIS – TYPES OF BONE FORMATION. STRUCTURE OF PERIOSTEUM💗

What is the composition of an embryo's skeleton during embryonic development?

Hyaline cartilage

By which week does the process of ossification begin in embryonic development?

By the 7th week

What are the main reasons for bone remodeling and repair of fractures?

To meet the expectations of lifestyle changes and for the repair of fractures

Which cells are involved in the growth , development , and remodeling of bones?

Osteoblasts , osteoclasts and osteocytes

What is the function of osteoblasts?

Bone - forming cells

What is the function of osteocytes?

bone deposition and resorption

What is the function of osteoclasts?

Break down and reabsorb bone

During embryonic development , what do osteoblasts turn into?

Osteocytes

What do osteogenic cells in the surrounding connective tissue differentiate into during embryonic development?

New osteoblasts

When does intramembranous ossification begin and continue?

Begins in utero during fetal development and continues into adolescence

What types of bones develop through intramembranous ossification?

Viscerocranial bones , neurocranial bones , clavicles

From what do compact and spongy bone develop directly in intramembranous ossification?

Mesenchymal sheets of connective tissue

What do osteoblasts at the surface of newly formed spongy bone become?

Cellular layer of periosteum

What does the periosteum secrete in intramembranous ossification

Compact bone superficially to spongy bone

What does the periosteum eventually condense into

Bone marrow

How is new bone constantly remodeled

Under the action of osteoclasts

How does bone development occur in endochondral ossification

By replacing hyaline cartilage

How does bone development occur in endochondral ossification

By replacing hyaline cartilage

What serves as the template for new bone in endochondral ossification

Cartilage

How long does the method of endochondral ossification take

Much longer than intramembranous ossification

Give an example of bones developed through endochondral ossification

Bones at the base of the skull

what point in development does endochondral ossification begin for long bones

After 6-8 weeks of conception

What do mesenchymal cells differentiate into during endochondral ossification

Chondroblasts

What do chondroblasts form in endochondral ossification

Hyaline cartilage precursor of bones

How does the cartilaginous model grow in size during endochondral ossification

By producing more matrix

What do blood vessels in the perichondrium bring to the edges of the structure during endochondral ossification

Osteoblasts

What do arriving osteoblasts deposit around the diaphysis

Bone in a ring

What do blood vessels later bring into the center of the structure in endochondral ossification

Osteogenic cells that differentiate into osteoblasts

What forms the medullary canal in endochondral ossification

Spaces formed by the action of osteoblasts and osteoclasts

Where do osteogenic cells deposit after birth in endochondral ossification

At epiphyseal regions

What is the thin plate of hyaline cartilage between the diaphysis and epiphysis called during adolescence

The growth plate

What is the " epiphyseal line "

The bone that replaces the growth plate when the cartilage disappears

What is the periosteum

Connective tissue that forms bony tissue and covers every part of the bone except cartilaginous articulations

What is the periosteum rich in

Blood vessels , lymph vessels , and nerve fibers

What are the layers of the periosteum

• Stratum osteogenicum : rich in cells inner layer . • Stratum fibrosum : poor in cells , outer layer

What factors affect bone formation

-Age
-Smoking
-Decrease in estrogen and testosterone
-Insufficient exercise
-Diet low in calcium and proteins
- Abnormal vitamin D receptors