endothelium

subendothelium

internal elastic membrane

Elastic membrane (retracts the expanded blood vessels)

Smooth muscle fibers (synthetic phenotype, contractile phenotype) (fibroblast subtype, produces collagen fibers, elastic fibers, matrix)

connective tissue

loose connective tissue

In larger arteries, there is an external elastic lamina (thin) at the junction of the media and adventitia.

Endothelium: many wp bodies

Subendothelial layer: thick, loose connective tissue, containing collagen fibers and a small amount of smooth muscle fibers

Internal elastic lamina: unclear boundary with tunica media

The thickest, 40-70 layers of elastic membrane arranged in concentric circles and a large number of elastic fibers

Circular smooth muscle fibers and collagen fibers

Thin, loose connective tissue, indistinct external elastic membrane, containing smooth muscle fibers

Endothelium: few wp bodies

Subendothelial layer: thin

Internal elastic membrane: obvious, wavy, well-defined

Thick, 10-40 layers of annular smooth muscle fibers, with a small amount of elastic fibers and collagen fibers in the intercellular spaces

Thickness similar to tunica media

loose connective tissue

Nutritive blood vessels and nerve fibers

The external elastic membrane is obvious

Internal elastic membrane is obvious

3-9 layers of circular smooth muscle fibers

No external elastic membrane

plasma membrane vesicles

substrate

When capillaries are damaged, pericytes can proliferate and differentiate into endothelial cells, smooth muscle fibers and fibroblasts

tight connection

Basement membrane intact

plasma membrane vesicles

Distributed in connective tissue, muscle tissue, exocrine glands, nervous system, thymus and lungs

Participate in the formation of barrier structures

tight connection

Basement membrane intact

The non-nucleated part of the cell is extremely thin, has endothelial windows that penetrate the cytoplasm, and is closed by a septum.

Distributed in gastrointestinal mucosa, endocrine glands and renal blood vessels

The lumen is large and irregular, and the endothelial cell gaps are large, making it easy for large molecules to enter and exit.

Incomplete or absent basement membrane

Distributed in liver, spleen, bone marrow and certain endocrine glands

Distribution, veins above 2mm

structure

Function: Prevent blood from flowing back

endothelium

heart valve

subendothelium

myocardial fiber

heart skeleton

Serosa: Loose connective tissue Mesothelial pericardial cavity

sinoatrial node

Atrioventricular node, atrioventricular bundle, left and right bundle branches

Synchronize contraction and relaxation of atrial and ventricular muscles

pacemaker cells

transference cells

Purkinje fiber