Collagen is a major structural component in the extracellular matrix (ECM) and in connective tissues such as tendons, ligaments, dermis, and blood vessels. As insoluble fibrous proteins, collagens are the primary determinant of ECM tensile strength and they help tissues withstand stretching. While there are at least 28 types of collagen, 80-90% of the collagen in the human body are types I, II, and III. The 3D Basic Embedded Tubule Formation Kit (3D-BETF) contains collagen type I, which is found in skin, tendon, vasculature, and bone ECM, as well as the accessory components needed to form a 3D collagen gel matrix. It also includes a serum free assay medium optimized to promote endothelial tubule formation within the collagen gels. Note: This kit does not include cells. For inclusive kits to create 3-dimensional scaffolds that includes primary cells, see ScienCell™’s 3D Embedded Tubule Formation Kit (Cat. #8708), ScienCell™’s Network Formation Assay Kit (Cat. #8718), and ScienCell™’s Endothelial–Pericyte Coculturing Kit (Cat. #8728).