Proteoglycans form an amorphous matrix, forming a structure similar to molecular sieves

Collagen fibrils composed of type II collagen

The fibers are so thin that they cannot be distinguished under a light microscope.

The refractive index is similar to that of the matrix and difficult to distinguish under a light microscope.

Mostly heavily intertwined elastane fibers

Very elastic

Parallel or staggered bundles of collagen fibers

Strong toughness

35% of bone weight

Mainly 90% collagen fibers

A small amount of amorphous matrix

There are also various proteins related to bone calcification, calcium ion transport, and adhesion between cells and bone matrix.

Accounts for 65% of bone weight

Calcification is the process of orderly deposition of inorganic salts into osteoid

The extracellular matrix of new bone tissue is osteoid without bone salt deposition.

bone matrix structural form

Collagen fibers are arranged in parallel layers and bonded to bone salt and amorphous matrix

Increased bone strength

Contains bone cells The fibers in two adjacent bone plates are perpendicular to each other Fibers within the same bone plate are parallel to each other Visible within cancellous bone

Located in the inner layer of periosteum and perichondrium

Bone and cartilage stem cells

When bone tissue grows, remodels, and repairs fractures, it becomes active and differentiates into osteoblasts.

derived from mesenchymal cells

Under the electron microscope, abundant rough endoplasmic reticulum and Golgi complex can be seen, as well as chondrocytes!

During osteogenesis

Osteoblasts gradually separate to form bone cells

Under the action of calcitonin, osteoblasts promote bone formation and blood calcium concentration decreases.

gap links between cells

Differentiated from mesenchymal cells

The spaces where bone cells are located are bone lacunae

There are blue-purple protrusions around the lacunae, which are bone canalicles.

Gap junctions formed between adjacent bone cell processes

The bone lacunae and canaliculus spaces contain a small amount of tissue fluid, which nourishes bone cells and takes away metabolic products.

Under the action of hormones, bone cells have certain osteolytic and osteogenic effects

Scattered on the surface of bone tissue

Has strong bone dissolving ability and contains a large amount of lysosomes

The bone matrix is ​​dissolved, calcium ions are increased, and blood calcium is increased. Complements each other with osteoblasts

Secrete a variety of hydrolases and organic acids

Nucleus ranges from 6 to 50 and is highly eosinophilic

fold edge

absorptive lacunae

derived from a single cell

ring bone plate

bone unit

interosseous plate

Penetrating fibers refer to the fibers that penetrate the bone from the periosteal membrane and have the function of fixing the periosteum and ligaments.

The adventitia is thick and is dense connective tissue

Inner layer containing osteoprogenitor cells

interosseous plate

Cells are small and dispersedly arranged

Chondrocytes divide into homogeneous cell groups and are arranged in longitudinal rows to form cell columns.

Chondrocyte degeneration and apoptosis

Visible transitional trabeculae