###### Created: 2024-01-12 15:17 ###### Areas & Topics: #medicine #embryology #physiology ###### Note Type: #permanent ###### Connected to: [[Capillaries]] - Vasculogenesis is the process by which a developing embryo begins to form brand new blood vessels which go on to create the circulatory system. - It is different from [[Angiogenesis]] as the formation of the blood vessels in vasculogenesis is de novo (i.e. vessels are made from newly produced cells). ### Process - Roughly three weeks after fertilisation, mesodermal cells (cells coming from the mesoderm in the trilaminar germ disc) will begin to differentiate into hemangioblasts (multipotent pre-cursor cells to blood and endothelial cells). - These hemangioblasts will then further differentiate into angioblasts (cells which go on to form the endothelium of blood vessels). - The angioblasts will then cluster together to form blood islands. - Blood islands are what go on to form the blood vessels themselves. - Intracellular clefts form inside the blood islands and begin to create the vessel lumens. - As this happens, cells on the periphery of the blood island flatten and begin to form the inner layers of the vessel wall. - Mesenchymal cells attach to the outside to form the outer muscular and connective tissue layers of the vessels. - The main vessels will then begin to fully form with [[Angiogenesis]] shortly following to continue developing the circulatory system. ![[461979_1_En_7_Fig1_HTML.jpg]] ![[3-s2.0-B9780128023853000061-f06-01-9780128023853.jpg]] ### Additional Information - Whilst the majority of vasculogenesis occurs embryonically, it can sometime occur in adulthood from endothelial progenitor cells. - Endothelial progenitor cells are stem cell derivatives, and are seen to cause vasculogenesis in cases such as tumour formation, neovascularisation or vascularisation following trauma (e.g. cardiac or retinal ischaemia) or endometriosis. ### Resources https://en.wikipedia.org/wiki/Vasculogenesis https://en.wikipedia.org/wiki/Blood_islands