Fibroblasts have been extensively used for a wide range of cellular and molecular studies as they are one of easiest types of cells to grow in culture. Their durability also makes them amenable to a variety of manipulations ranging from studies employing gene transfection to microinjection. In general, fibroblasts secrete a non-rigid extracellular matrix (ECM) which is rich in type I and/or type III collagen. There is evidence showing that fibroblasts in various organs are intrinsically different. A previous study demonstrated that thymic fibroblasts are derived from the embryonic neural crest, which first surrounds the thymus as mesenchyme and later migrates into the thymic epithelium to form a network of fibroblasts. Thymic fibroblasts and the associated ECM have been shown to be responsible for normal thymus morphogenesis and lymphopoiesis. HTyF from ScienCell Research Laboratories are isolated from the human fetal atrium. HTyF are cryopreserved at passage one and delivered frozen. Each vial contains >5 x 105 cells in 1 ml volume. HTyF are characterized by immunofluorescence with antibody specific to fibronectin. HTyF are negative for HIV-1, HBV, HCV, mycoplasma, bacteria, yeast, and fungi. HTyF are guaranteed to further expand for 15 population doublings under the conditions provided by ScienCell Research Laboratories. Recommended Medium It is recommended to use Fibroblast Medium (FM, Cat. #2301) for culturing HTyF in vitro.