Fibroblasts are mesenchymal cells and secrete a non-rigid extracellular matrix that is rich in type I and/or type III collagen. They are responsible for much of the synthesis of extracellular matrix in connective tissues and play major roles in wound healing. Many diseases involve fibroblasts; either because their etiology involves fibroblasts or because of the fibrosis that accompanies damage to other cell types. Origin of thymic fibroblasts came 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 their ECM are responsible for normal thymus morphogenesis and lymphopoiesis. Human Thymic Fibroblasts are usefull tools for understanding physiological and pathophysiological relevance in Thyroid gland function and disease.