Large amount of collagen fibers (type I collagen) Small amount of amorphous matrix

It is called bone salt, mainly fine needle-shaped hydroxyapatite crystal

Bone

The rough endoplasmic reticulum and Gorgi complex are developed

Osteoblasts become flat when they are relatively stationary and close to bone tissue

Have slender protrusions

The cavity where the osteocyte cell body is located is called the bone trap, and the cavity occupied by the protrusion is called the bone tubules. The bone traps are connected to each other through the bone tubules. The adjacent osteocyte protrusions are connected by gaps and contain tissue fluid, which can nourish bone cells and transport metabolic substances.

A certain osteogenesis and osteolysis effect

Participate in regulating calcium and phosphorus balance

LM

EM

Osteolysis

Havers bone plate central tube

The central tube is connected to the through-tube, and its wall contains periosteal tissue and the lumen contains capillaries and nerves.

Treatment of periosteum and bone defects

At the site to be osteogenesis, mesenchymal first differentiates into the original connective tissue membrane, where the mesenchymal cells are then differentiated into osteoblasts, which are further differentiated into osteoblasts.

First, the part where the bone tissue is formed is called the ossification center. As the ossification continues, the bone trabecula is formed. The osteoblasts on its surface continue to add new bone tissue, making the bone trabecula grow and thicker.

The scope of the trabecular bone gradually expanded into cancellous bone: later, the surface of the cancellous bone was gradually converted into dense bone.

The connective tissue around the osteogenic area differentiates into periosteum accordingly

Mesenchymal cells-bone progenitor cells-chondrocytes-chondrocytes, which proliferate and secrete cartilage matrix. Because the matrix shape is similar to bone, it is called cartilage prototype

The middle section of the prototype, bone progenitor cells differentiate into osteoblasts, which form a thin primitive bone tissue in the shape of a collar circle and wraps around the middle section of the prototype, called the bone collar

The middle section of the prototype is apoptosis of chondrocytes, cartilage ossification, osteoclasts dissolve and absorb degenerated cartilage, forming a tunnel consistent with the long axis of the bone. Osteoblasts attach to other cartilage matrixes, forming a cord-like structure with the calcified cartilage matrix as the axis, surrounding the new bone tissue, which is called transitional bone trabecular, and the part where this structure appears is called the primary ossification center.

The secondary ossification center appears in the center of the cartilage at both ends of the backbone, and the time it appears varies from bone, mostly several months or years after birth. The osteogenesis process is similar to the primary ossification center, which is radial from the center to the surroundings. The epiphyseal is eventually formed by bone tissue replacing the cartilage. A layer of cartilage on the epiphyseal surface is never ossified, that is, articular cartilage. A layer of cartilage is retained between the epiphyseal and the backbone, called the epiphyseal plate, which is the structural basis for the growing long bones.

Cartilage reserve area

Cartilage hyperplasia area

Cartilage mature area

Cartilage calcification zone

Osteogenesis area

There is a substrate containing more chondroitin sulfate around the trap, called the cartilage capsule, and HE staining is highly basophilic.

The surrounding cartilage is childish, small, flat and round, and is distributed individually

In the middle of cartilage, cells are mature, large in size, weak basophilic in the cytoplasm, and cell populations are distributed (2-8, formed by proliferation of one chondrocyte, called homologous cell population)

Rich coarse endoplasmic reticulum and Golgi complex can be observed under EM

Generate cartilage matrix

Amorphous matrix fiber

The main components of amorphous matrix

It is essentially a cartilage matrix