Fibroblast 66847 225199688 2008-07-12T12:32:15Z Robert M. Hunt 2049578 Deleting untrue statement: "Fibroblasts were first discovered by Dr. Matthias De Oliveira in 1968." {{Merge|Fibrocyte|Talk:Fibroblast#Merger proposal|date=January 2008}} '''{{Unreferenced|date=January 2007}} [[Image:NIH 3T3.jpg|thumb|250px||right|NIH/3T3 Fibroblasts in [[cell culture]]]] A '''fibroblast''' is a type of [[cell (biology)|cell]] that synthesizes and maintains the [[extracellular matrix]] of many [[animal]] tissues. Fibroblasts provide a structural framework ([[Stroma (animal tissue)|stroma]]) for many tissues, and play a critical role in [[wound healing]]. They are the most common cells of [[connective tissue]] in animals. The main function of fibroblasts is to maintain the structural integrity of connective tissues by continuously secreting precursors of the extracellular matrix. Fibroblasts secrete the precursors of all the components of the extracellular matrix, primarily the [[ground substance]] and a variety of [[fibres]]. The composition of the extracellular matrix determines the physical properties of connective tissues. Fibroblasts are morphologically heterogeneous with diverse appearances depending on their location and activity. Though morphologically inconspicuous, [[ectopic]]ally transplanted fibroblasts can often retain [[positional memory]] of the location and tissue context where they had previously resided, at least over a few generations. Unlike the [[epithelial]] cells lining the body structures, fibroblasts do not form flat monolayers and are not restricted by a polarizing attachment to a [[basal lamina]] on one side, although they may contribute to basal lamina components in some situations (eg subepithelial [[myofibroblasts]] in [[intestine]] may secrete the α-2 chain carrying component of the [[laminin]] which is absent only in regions of follicle associated epithelia which lack the myofibroblast lining). Fibroblasts can also migrate slowly over substratum as individual cells, again in contrast to epithelial cells. While epithelial cells form the lining of body structures, it is fibroblasts and related connective tissues which sculpt the "bulk" of an organism. == Embryologic origin == Like other cells of connective tissue, fibroblasts are derived from primitive [[mesenchyme]]. Thus they express the intermediate filament protein [[vimentin]], a feature used as a marker to distinguish their mesodermal origin. However, this test is not specific as epithelial cells cultured in vitro on adherent substratum may also express vimentin after some time. In certain situations epithelial cells can give rise to fibroblasts, a process called [[epithelial-mesenchymal transition]] (EMT). Conversely, fibroblasts in some situations may give rise to epithelia by undergoing a [[mesenchymal to epithelial transition]] (MET) and organizing into a condensed, polarized, laterally connected true epithelial sheet. This process is seen in many developmental situations (eg. [[nephron]] and [[notocord]] development). == Structure and function == Fibroblasts have a branched [[cytoplasm]] surrounding an elliptical, speckled [[cell nucleus|nucleus]] having one or two [[nucleoli]]. Active fibroblasts can be recognized by their abundant rough [[endoplasmic reticulum]]. Inactive fibroblasts, which are also called '''fibrocytes''', are smaller and spindle shaped. They have a reduced rough endoplasmic reticulum. Although disjointed and scattered when they have to cover a large space, fibroblasts when crowded often locally align in parallel clusters. Fibroblasts make [[collagen]]s, [[glycosaminoglycan]]s, [[reticular fiber|reticular]] and [[elastic fibers]], and [[glycoprotein]]s found in the [[extracellular matrix]]. Growing individuals' fibroblasts are dividing and synthesizing ground substance. Tissue damage stimulates fibrocytes and induces the [[mitosis]] of fibroblasts. == Secondary actions == [[Mouse embryonic fibroblasts]] (MEFs) are often used as "feeder cells" in human embryonic [[stem cell]] research. However, many researchers are gradually phasing out MEF's in favor of culture media with precisely defined ingredients of exclusively human derivation. Further, the difficulty of exclusively using human derivation for media supplements is most often solved by the use of "defined media" where the supplements are synthetic and achieve the primary goal of eliminating the chance of contamination from derivative sources. ==See also== * [[fibrocartilage callus]] * [[Fibrous connective tissue]] * [[3T3 cells]] ==External links== * {{eMedicineDictionary|fibroblast}} * {{UIUCHistologySubject|240}} * {{LoyolaMedEd|Histo/practical/ctproper/hp3-15.html}} {{Connective tissue}} ''' [[Category:Non-terminally differentiated (blast) cells]] [[ca:Fibroblast]] [[de:Fibroblast]] [[es:Fibroblasto]] [[fa:فیبروبلاست]] [[fr:Fibroblaste]] [[he:פיברובלסט]] [[it:Fibroblasto]] [[ja:線維芽細胞]] [[lt:Fibroblastas]] [[mk:Фибробласт]] [[nl:Fibroblast]] [[pl:Fibroblast]] [[pt:Fibroblasto]] [[ru:Фибробласт]] [[sk:Fibroblast]] [[sr:Фибробласт]] [[sv:Fibroblast]] [[tr:Fibroblast]] [[zh:成纤维细胞]]