Fibroblast
Fibroblastus
Also known as: fibrocyte, myofibroblast, tenocyte
The principal resident cell of connective tissue, which synthesises and remodels the extracellular matrix — collagen, elastic and reticular fibres and ground substance.
Overview
Active fibroblasts are large, flat, spindle- or star-shaped cells with long processes, a pale oval nucleus with a prominent nucleolus, and basophilic cytoplasm rich in RER and Golgi — they synthesise procollagens (types I, III and others), elastin, fibrillin, proteoglycans and adhesive glycoproteins, and the MMPs that degrade matrix. Quiescent cells (sometimes called fibrocytes) are smaller and spindle-shaped with dark, elongated nuclei and little cytoplasm; they can be reactivated by injury. Fibroblasts are derived from mesenchymal cells, are among the most proliferative cells of connective tissue and express vimentin.
In wound healing, fibroblasts stimulated by TGF-β and PDGF migrate into the wound, proliferate and lay down granulation tissue (initially type III collagen, later replaced by type I). Some become myofibroblasts, which contain α-smooth-muscle actin stress fibres and pull the wound edges together (wound contraction). Specialised fibroblast-like cells include reticular cells (lymphoid stroma), tenocytes (tendons), hepatic stellate (Ito) cells, and type B synoviocytes.
- Location
All connective tissues proper; dermis, tendons, ligaments, organ capsules and stroma, lamina propria.
Anatomy
- Histology
Elongated, wavy, dark nuclei lying between collagen bundles; cytoplasm hard to distinguish from collagen in H&E.
Function
- Synthesis and secretion of collagen, elastic fibres and ground substance.
- Remodelling of the matrix (MMPs and TIMPs).
- Wound healing and scar formation; wound contraction (myofibroblasts).
- Production of growth factors and cytokines; organisation of tissue architecture.
Clinical significance
Fibrosis
Persistent injury and TGF-β signalling make fibroblasts/myofibroblasts (and hepatic stellate cells) deposit excess collagen — cirrhosis, idiopathic pulmonary fibrosis, systemic sclerosis, chronic kidney disease. Antifibrotics (pirfenidone, nintedanib) slow lung fibrosis.
Contractures and fibromatosis
Myofibroblast proliferation in the palmar aponeurosis causes Dupuytren contracture; excess wound contraction after burns causes disabling contractures.
Compiled from standard anatomy and physiology references — see the Cells & Tissues sources. For education only; not medical advice.