Endothelium is a kind of epithelium composed of a layer of squamous cells (endothelial cells) that lines the inner surface of the heart, lymphatic vessels and blood vessels, and other tube-shaped vessels. The layer basically forms a link between blood and lymph fluid in the lumen and other vessels. Endothelium cells that are in contact with circulating blood are referred to as vascular endothelial cells while those in contact with the lymph are referred to as the lymphatic endothelial cells.
Mesothelium cells on the other hand are contained in a layer of specialized simple squamous epithelial cells that line the internal organs and body wall in the pleural, peritoneal, and pericardial cavities. They also surround the male internal reproductive organs (the tunica vaginalis testis) and those of women (tunica serosa uteri). Mesothelium that covers the internal organs of the body is referred to as visceral mesothelium while the layer that covers the body walls are known as parietal mesothelium. The main function of mesothelium is to produce a lubricating fluid that is released between layers, thereby providing a protective surface that is slippery and non-adhesive to enable intracoelomic movement.
Difference in Cytoplasm Concentration
Endothelium and mesothelium cells have different cytoplasm concentrations where endothelium has little to none concentration, whilst mesothelium tend to contain high levels of cytoplasm. The other difference between the two is that endothelium directly contacts lymph and blood, draining interstitial fluid and fighting infections.
Difference in Location
In regard to location, mesothelium cells are found in all the serous membranes of the body such as pericardial, pleura, peritoneum, and internal reproductive organs. On the other hand, endothelium cells are found in the inner surface of the blood vessels, lymphatic vessels, and the heart.
Difference in Origin
Mesothelium originates from the embryonic mesoderm cell layer that lines the body cavity (coelom) in the embryo. It then develops into a layer of cells (mesothelium cells) that cover and protect a majority of the internal organs in the body.
Endothelium cells on the other hand originate from the hemangioblast, which is a mesoderm-derived (endoderm and ectoderm) progenitor cell that gives rise to hematopoietic stem cells and to angioblasts, which are the precursors of endothelial cells.
Medical Conditions Associated with Endothelium and
Alterations of endothelium cells and the vasculature play a big role in the pathogenesis of a broad spectrum of some of the most dangerous disease. If the endothelium gets damaged and the NO levels become imbalanced, the cells which are supposed to remain in the blood leak through the blood vessels and into the adjacent body tissue. Endothelium dysfucntion is associated with medical conditions such as heart disease, stroke, peripheral vascular disease, chronic kidney failure, viral infections, venous thrombosis, including others.
When mesothelium cells suffer damage in their DNA, certain changes occur. Changes in these genes cause the cells to grow out of control, leading to various medical conditions. For example, prolonged exposure to asbestos causes damage to the mesothelium lining, which results to mesothelioma, a rare form of cancer that affects the lungs, abdomen, heart, and the testicles. Damage of mesothelium cells also leads to lung cancer.
How to Identify Mesothelium and Endothelium
After decades of research, scientists have now found various cell markers that are specific for endothelial cells. They’ve also discovered that mesothelium cells have monoclonal antibodies and that they do not synthesize and secrete VWF (von Willebrand factor).