blood cell fragments used to clot blood are called

The platelets are the small, bright purple fragments. Platelets: A blood slide of platelets aggregating, or, clumping together. Local application of these platelet-produced healing-associated factors in increased concentrations has been used as an adjunct to wound healing for several decades.

These growth factors play a significant role in the repair and regeneration of connective tissues. They also release wound healing-associated growth factors including platelet-derived growth factor (PDGF), which directs cell movement TGF beta, which stimulates the deposition of extracellular matrix tissue into a wound during healing and vascular endothelial growth factor (VEGF), which stimulates angiogenesis, or the regrowth of blood vessels. During coagulation, they release factors that increase local platelet aggregation (thromboxane A), mediate inflammation (serotonin), and promote blood coagulation through increasing thrombin and fibrin (thromboplastin). Platelets secrete many factors involved in coagulation and wound healing. The complex process of wound repair can only begin once the clot has stopped bleeding. The adhesive surface proteins of platelets allow them to accumulate on the fibrin mesh at an injury site to form a platelet plug that clots the blood. Platelets circulate in blood plasma and are primarily involved in hemostasis (stopping the flow of blood during injury), by causing the formation of blood clots, also known as coagulation. One platelet can be seen in the upper left side of the image (purple) and is significantly smaller in size than the red blood cells (stained pink) and the two large neutrophils (stained purple). Platelet: Image from a light microscope (40×) from a peripheral blood smear surrounded by red blood cells. They are about 1/10 th to 1/20 th as abundant as white blood cells. Less than 1% of whole blood consists of platelets. Platelets also contain adhesive proteins that allow them to adhere to fibrin mesh and the vascular endothelium, as well as to a microtubule and microfilament skeleton that extends into filaments during platelet activation.

However, they do contain mitochondria and mitochondrial DNA, as well as endoplasmic reticulum fragments and granules from the megakaryocyte parent cells. Because they lack a nucleus, they do not contain nuclear DNA.

Platelets are not true cells, but are instead classified as cell fragments produced by megakaryocytes. Platelets are irregularly shaped, have no nucleus, and typically measure only 2–3 micrometers in diameter.

Blood cell fragments used to clot blood are called