Features: Presence of stem cells, active proliferation, complete regeneration

Examples: epidermal cells, cells covering the mucosa of the respiratory tract and digestive tract, cells covering the lumen of reproductive organs, red blood cells, platelets, and white blood cells.

Characteristics: Quiescent cells, in the G0 phase, enter the G1 phase after tissue damage, and some can be completely regenerated.

Examples: parenchymal cells of various glands or gland-like organs, such as pancreas, salivary glands, endocrine glands, sweat glands, sebaceous glands and epithelial cells of renal tubules, etc.

Features: No ability to divide and proliferate

Examples: nerve cells, skeletal muscle cells and cardiomyocytes

Mesenchymal stem cells, hematopoietic stem cells (with self-sustainability and self-renewal capabilities, plasticity)

The raised part of the hair follicle is rich in stem cells

Liver stem cells are distributed in or near the bile duct. Mainly differentiates into liver cells, bile duct cells, and then oval cells

Skeletal muscle stem cells, also called satellite cells, are distributed in muscle fibers and mainly differentiate into skeletal muscle fibers.

Hepatocyte regeneration: after hepatectomy; hepatocyte necrosis, mesh scaffold is not damaged; hepatocyte extensive necrosis, scaffold collapse); stem cells present in Herring duct differentiate into hepatocytes and bile duct epithelial cells

Tubular gland regeneration: whether the basement membrane is damaged

fully renewable

Cartilage regeneration ability is weak, and when the cartilage tissue defect is large, fibrous tissue participates in repairing it. Bone tissue has strong regeneration ability and can be completely repaired after fractures

Capillary regeneration is completely regenerated by sprouting; large blood vessel smooth muscle scar repair

The regeneration ability of muscle tissue is very weak. The regeneration ability is smooth muscle > striated muscle > cardiac muscle.

Nerve cells in the brain and spinal cord cannot regenerate after damage, and are repaired by glial cells and their fibers. If the regenerated axons cannot reach the distal end and are mixed with the proliferated connective tissue, curling into a ball and forming a traumatic neuroma, intractable pain may occur.

It is composed of new thin-walled capillaries and proliferated fibroblasts, accompanied by infiltration of inflammatory cells. To the naked eye, it is bright red, granular, soft and moist, and looks like fresh granulation. Granular reason: the new capillary network is loop-like.

Anti-infection and wound protection

Fill wounds and other tissue defects

Organized or encapsulated necrosis, thrombus, inflammatory exudates and other foreign bodies

Granulation tissue maturation - fibrous connective tissue - scar tissue

Fill and connect injured wounds or other defects for a long time to maintain the integrity of tissues and organs

Maintain the robustness of tissues and organs

scar shrinkage

scarring adhesions

Excessive scar tissue proliferation, also known as hypertrophic scars

growth factors and receptors

extracellular matrix

fibroblast proliferation

extracellular matrix accumulation

interstitial collagenase

Gelatinase

Matrilysin

Model metalloproteinase

early changes

Wound edge shrinkage

Granulation tissue proliferation and scarring

Regeneration of epidermis and other tissues

primary healing

secondary healing

Hematoma formation (within hours)

Fibrous callus formation (2, 3 days to 2 weeks)

Bone callus formation (weeks)

Callus reconstruction or reshaping (6---12 months)

Timely and correct reduction of fracture ends

Timely and reliable fixation of broken ends

Carry out systemic and local functional exercises as soon as possible to maintain good local blood supply

age

Nutrition

Infection and foreign bodies

local blood circulation

innervation

ionizing radiation