Fibroblasts are useful 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 wide variety of manipulations ranging from studies employing gene transfection to microinjection. There is evidence that fibroblasts in various parts of the body are intrinsically different. Fibroblasts secrete a non-rigid extracellular matrix that is rich in type I and/or type III collagen. Fibroblasts are responsible for much of the synthesis of extracellular matrix in connective tissues. They also and play a major role in wound healing. Many diseases require fibroblasts actions, either because fibroblasts are related with their etiology or because of the fibrosis that accompanies damage to other cell types in tissues. Human Tonsil Fibroblasts are also useful tools to stablish in vitro disease models for High Throughput and High Content Screening.