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The blood–ocular barrier is a barrier created by endothelium of capillaries of the retina and iris, ciliary epithelium and retinal pigment epithelium. [1] It is a physical barrier between the local blood vessels and most parts of the eye itself, and stops many substances including drugs from traveling across it. [2]
Retinal blood vessels that are similar to cerebral blood vessels maintain the inner blood-ocular barrier. This physiological barrier comprises a single layer of non-fenestrated endothelial cells, which have tight junctions. These junctions are impervious to tracer, so many substances can affect the metabolism of the eyeball.
These in turn unite and form veins which pass along the sides of the renal pyramids. The descending vasa recta have a non-fenestrated endothelium that contains a facilitated transport for urea; the ascending vasa recta have, on the other hand, a fenestrated endothelium.
There are three different types of capillaries: continuous, fenestrated, and sinusoidal also called discontinuous. In continuous capillaries the endothelial cells are tightly spaced, allowing only small molecules like ions or water to diffuse through the intercellular clefts (the gaps between the endothelial cells).
Fenestrated capillaries have diaphragms that cover the pores whereas sinusoids lack a diaphragm and just have an open pore. These types of blood vessels allow red and white blood cells (7.5 μm – 25 μm diameter) and various serum proteins to pass, aided by a discontinuous basal lamina.
In microanatomy, fenestrae are found in endothelium of fenestrated capillaries, enabling the rapid exchange of molecules between the blood and surrounding tissue. [4] The elastic layer of the tunica intima is a fenestrated membrane.
The post Passive vs. Non-Passive Income: What's the Difference? appeared first on SmartReads by SmartAsset. The key to effective financial planning are two primary types of income: Passive and non ...
The LSECs make up around half of the non-parenchymal cells in the liver and are flattened and fenestrated. [4] LSECs have many fenestrae that gives easy communication between the sinusoidal lumen and the space of Disse. They play a part in filtration, endocytosis, and in the regulation of blood flow in the sinusoids. [5]