Tunica intima: Layer of the endothelial cells, underneath basal lamina Subendothelial layer: loose connective tissue with some smooth muscleTunica media: Smooth muscle cells and elastic and reticular fibers, collagen type I, proteoglycans no characteristic or absent in veinsTunica adventitia: mainly consists of connective tissue (longitudinally arranged collagen and elastic fibers, collagen type III) well-developed in veins (smooth muscle cells can be found) Vasa vasorum, vascular nervesIn muscular arteries internal elastic lamina (I. E. L.) separates the t. media from t. intima. Between the t. media and t. adventitia, the external elastic lamina (E. E. L.) is found.
- Increasing number of muscle cells, decreasing amount of fibersT. intima: endothelial layer, basal lamina, subendothelial layer I. E. L.: between t. intima and media, irregular, wavy lines (orcein and resorcin-fuchsin stain the lamina)T. media: concentrically oriented smooth muscle cells intermingled with some elastic and collagen fibers and fibrocytesT. adventitia: E. E. L.: in larger arteries, longitudinal elastic fibers poorly developed, collagen fibers, fibrocytes, fat cells vasa vasorum, vascular nerves
1. Continuous / somatic capillaries basal lamina is continuous Skeletal muscle, lungs, connective tissue, brain2.a Fenestrated / visceral capillaries with diaphragm large feneastrae in the wall of endothelial cells their diamater is between 60-70 nm Diaphragm (macromolecular filter) Intense interchange of substances: resorptive epithelium of small intestine, epihtelium of renal tubuli, epihtelium of the endocrine organs2.b Fenestrated capillaries without diaphragm Basal lamina is thick Renal glomeruli3. Discontinuous sinusoidal capillaries Enlarged diameter, irregular shape maybe with pores Liver, lymph node, spleen
- They have thinner wall, bigger lumen than the arteries haveT. intima: - endothel layer, basal lamina subendothelial layer - at the border of the t. media, there is an increasing number of the elastic fibersT. media: - thin layer - the smooth muscle cells are loosely situated, - collagen fibers and fibrocytesT. adventitia: - the widest layer of the veins, rich of elastic fibers - longitudinal smooth muscle cells in the large veins - vasa vasorum (vessels of the vessels)
To study the structure of the wall of thedifferent blood vessels