Venule

A venule (Latin venules, German rarely venule ) is a small vein. Venules are the finest yet visible to the naked eye blood vessels to the arterioles. They can be seen as a fine vascular pattern ( Episcleralgefäße ) eg on the sclera ( sclera ) of the eye.

Venules arise from the venous portion of capillaries and unite with neighboring venules to veins. My basic structure is similar to that of veins, but they do not have significant layer of smooth muscle ( tunica media ), and no venous valves. In leukocyte migration, whereas an immune response, there is the influx of leukocytes to the lymph nodes via so-called hochendotheliale venules.

Various thick venules differ somewhat in structure, is divided so that after postcapillary venules with a diameter of 10 to 30 micrometers, collecting venules ( 30-50 microns) and muscular venules ( 50-100 microns). The walls of the collecting venules in addition pericytes single, branched smooth muscle cells. It was not until the muscular venules have one layer of overlapping branched smooth muscle cells. The subsequent veins have two or more layers of smooth muscle cells.

Itemization

• Circulatory system
• Vein
• Histology of the circulatory organs