| Fibroblast |
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NIH/3T3 Fibroblasts in cell culture
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| Latin |
fibroblastus |
| Code |
TH H2.00.03.0.01002 |
A fibroblast is a type of cell that synthesizes the extracellular matrix and collagen,[1] the structural framework (stroma) for animal tissues, and plays a critical role in wound healing. Fibroblasts are the most common cells of connective tissue in animals.
Contents
- 1 Background information
- 2 Embryologic origin
- 3 Structure and function
- 4 Secondary actions
- 5 See also
- 6 References
- 7 External links
Background information
Fibroblasts and fibrocytes are two states of the same cells, the former being the activated state, the latter the less active state, concerned with maintenance and tissue metabolism. Currently, there is a tendency to call both forms fibroblasts. The suffix "blast" is used in cellular biology to denote a stem cell or a cell in an activated state of metabolism.
Fibroblasts are morphologically heterogeneous with diverse appearances depending on their location and activity. Though morphologically inconspicuous, ectopically transplanted fibroblasts can often retain positional memory of the location and tissue context where they had previously resided, at least over a few generations. This remarkable behavior may lead to discomfort[clarification needed] in the rare event that they stagnate there excessively.
Embryologic origin
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 fibers. The composition of the extracellular matrix determines the physical properties of connective tissues.
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 (e.g. nephron and notocord development), as well as in wound healing and tumorigenesis.
Structure and function
Microfilaments, Mitochondria, and Nuclei in Fibroblast Cells
Fibroblasts have a branched cytoplasm surrounding an elliptical, speckled nucleus having two or more nucleoli. Active fibroblasts can be recognized by their abundant rough endoplasmic reticulum. Inactive fibroblasts, which are also called fibrocytes[citation needed], 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 collagens, glycosaminoglycans, reticular and elastic fibers, glycoproteins found in the extracellular matrix, and cytokine TSLP. Growing individuals' fibroblasts are dividing and synthesizing ground substance. Tissue damage stimulates fibrocytes and induces the mitosis of fibroblasts.
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 (e.g. 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.
The life span of a fibroblast, as measured in chick embryos, is 57 ± 3 days.[2]
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 MEFs in favor of culture media with precisely defined ingredients of exclusively human derivation[citation needed]. 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
- 3T3 cells
- Fibrocartilage callus
- Fibrous connective tissue
References
- ^ "Fibroblast". Genetics Home Reference. U.S. National Library of Medicine. 2014-05-05. Retrieved 2014-05-10.
- ^ Weissmanshomer, P.; Fry, M. (1975). "Chick embryo fibroblasts senescence in vitro: Pattern of cell division and life span as a function of cell density". Mechanisms of Ageing and Development 4 (2): 159–166. doi:10.1016/0047-6374(75)90017-2. PMID 1152547. edit
External links
- UIUC Histology Subject 240
- MedEd at Loyola Histo/practical/ctproper/hp3-15.html
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Connective Tissue (TH H2.00.03)
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| Physiology |
- Soft tissue
- Fibrosis
- Scarring
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| Classification |
| Connective tissue proper |
| Loose |
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| Dense |
- Dense irregular connective tissue
- Dense regular connective tissue
- Ligament
- Tendon
- Aponeurosis
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| Embryonic |
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| Specialized |
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| Composition (Histology) |
| Cells |
| Resident |
- Fibroblast
- Fibrocyte
- Reticular cell
- Tendon cell
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Wandering
cell |
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Extracellular
matrix
(noncellular) |
| Ground substance |
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| Fibers |
- Elastic fibers: Elastin
- Fibrillin
- EMILIN1
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See also: Template:Soft tissue tumors and sarcomas
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noco (i/b/d/q/u/r/p/m/k/v/f)/cong/tumr (n/e/d), sysi/epon
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proc, drug (D2/3/4/5/8/11)
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anat (h/n, u, t/d, a/p, l)/phys/devp/hist
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noco (m, s, c)/cong (d)/tumr, sysi/epon, injr
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Human cell types / list derived primarily from mesoderm
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| Paraxial |
Cartilage/bone/
muscle
(MSC) |
| OCP |
| bone: |
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| cartilage: |
- Chondroblast → Chondrocyte
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| Myofibroblast |
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| muscle: |
- Myoblast → Myocyte
- Myosatellite cell
- Tendon cell
- Cardiac muscle cell
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| adipose: |
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| Digestive system |
- Interstitial cell of Cajal
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| Intermediate |
| Urinary system (RSC) |
- Angioblast → Endothelial cell
- Mesangial cell
- Intraglomerular
- Extraglomerular
- Juxtaglomerular cell
- Macula densa cell
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- Stromal cell → Interstitial cell → Telocytes
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- Simple epithelial cell → Podocyte
- Kidney proximal tubule brush border cell
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| Reproductive system |
- Sertoli cell
- Leydig cell
- Granulosa cell
- Peg cell
- germ cells
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Lateral plate/
hemangioblast |
Blood/immune
(HSC) |
| Lymphoid (CFU-L) |
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| Myeloid (CFU-GEMM) |
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| Circulatory system |
- Endothelial progenitor cell
- Endothelial stem cell
- Angioblast/Mesoangioblast
- Pericyte
- Mural cell
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anat (c/f/k/f, u, t/p, l)/phys/devp/cell
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noco/cong/tumr, sysi/epon, injr
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noco/acba/cong/tumr, sysi/epon, urte
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proc/itvp, drug (G4B), blte, urte
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anat (a:h/u/t/a/l,v:h/u/t/a/l)/phys/devp/cell/prot
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noco/syva/cong/lyvd/tumr, sysi/epon, injr
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proc, drug (C2s+n/3/4/5/7/8/9)
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