The mechanical strength of connective tissue varies widely, from the stiffness and hardness of bone to the squishiness of many organs. In between are types. The term 'connective tissue' makes us think of something that 'connects'. The term is convenient for its brevity, but this type of tissue does a lot more than just. Fibers of connective tissue: Connective tissue fibers are of three principal types: Collagen fibers. Reticular fibers. Elastic fibers. 1. Collagen fibers are flexible and .
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raudone.infot Kumar Professor. Anatomy K G M U Lko. CONNECTIVE TISSUE. • GENERAL FEATURES. •. 1. Cells. 2. Matrix. -Fibers. -Ground substance. Fibers- many types. › Collagen fibers- white, strong. › Elastic fibers- yellow, stretch and recoil. › Reticular- fine collagen fibers that form internal structure for . Components of Connective Tissue. Matrix. The matrix of connective tissue can composed of fibers which are produced by fibroblasts such as.
When added to cultured human skin fibroblasts, CTGF dramatically increases synthesis of collagen, integrin, and fibronectin, 3 and subcutaneous injections of CTGF into mice produce granulation tissue and fibrosis in the skin.
CTGF mRNA was significantly elevated in the left ventricles of rat hearts after myocardial infarction, which correlated well with concomitant increases in fibronectin and type I and type III collagen mRNA levels and development of cardiac fibrosis in the animal hearts.
Elevated CTGF protein and mRNA levels were found in sclerotic skin fibroblasts, 9 specimens of inflammatory bowel disease, 10 and retrocorneal membranes, 11 and overexpression of CTGF was linked to human renal fibrosis.
The CTGF system has not been investigated in corneal wound healing.
33.2B: Connective Tissues: Loose, Fibrous, and Cartilage
Materials and Methods Cell Culture Cultures of human corneal fibroblasts were established by outgrowth from corneal explants, as described previously.
Cell from cultures between passages 2 and 5 were used for all experiments. CTGF Immunocytochemistry in Human Fibroblast Cultures Human corneal fibroblasts were seeded into well plates and grown to confluence in serum-supplemented medium. Cells expressing CTGF were then detected immunohistologically using a standard avidin-biotin amplification method. Fibroblasts were then sequentially incubated with goat anti-human CTGF for 1 hour at room temperature, washed three times with Tris-buffered saline TBS , incubated with biotinylated horse anti-goat IgG secondary antibody Vector Laboratories, Burlingame, CA , washed, incubated with alkaline phosphatase—conjugated streptavidin Dako, Carpinteria, CA , washed, and incubated with alkaline phosphatase visualization substrate Vector Red; Vector Laboratories.
Eyelashes and whiskers surrounding the eye were removed from the visual field.
A drop of proparacaine HCl 0. Bilateral excimer laser photorefractive keratectomy was performed. After excimer laser treatment, tobramycin 0. No postoperative topical steroid was administered.
At 1, 3, 7, 11, 14, and 21 days after excimer laser ablation, rats were killed by peritoneal injection of pentobarbital. Four rats were killed at each time point. Three rats from each time point were used for protein and RNA analyses. One rat from each time point was used for immunohistochemistry.
Eight corneas from four rats that did not undergo excimer ablation were used as the normal control day 0. Total RNA was extracted from each sample by using chloroform, precipitated with isopropanol and washed with ethanol.
Louis, MO in sodium carbonate, bicarbonate buffer and 0. Reactions were assembled in a well optical reaction plate. Collagen Synthesis Assay Collagen synthesis by human corneal fibroblasts was measured by 3H-proline incorporation, as described previously.
The scrambled mer oligonucleotide control was a random mixture of AGCT bases. Addition of oligonucleotides to the culture medium penetrated membranes, accesses cellular mRNA, and reduces levels of target gene mRNA. The collagen was precipitated and washed with 0.
Control experiments included omitting the sample RNA, reverse transcriptase, or both reverse transcriptase and Taq polymerase. PCR products were visualized on a 1. A unique restriction site PstI was used to cleave the predicted bp product into and bp fragments before visualization.
Slides were deparaffinized and rehydrated with xylene and a graded series of ethanol. The antibody was shown to be neutralizing by using the appropriate control, as shown previously.
Because the antisense oligonucleotide and neutralizing antibody to CTGF did not reduce collagen synthesis to levels below that with serum-free cultures, CTGF does not appear to mediate the basal level of collagen synthesis of corneal fibroblasts grown on plastic.
Furthermore, the effects of the neutralizing antibody and the antisense oligonucleotide are not due to nonspecific toxicity of the reagents. This localization is most likely due to increased levels of newly synthesized CTGF protein in the Golgi and secretory pathway.
Furthermore, the mRNA levels progressively increased and remained statistically higher than normal corneas through day 21, reaching approximately fold higher levels than in noninjured corneas.
Levels of CTGF protein tended to decrease during the first 3 days after PRK, perhaps reflecting fewer epithelial cells in the healing corneas. Beginning at day 7 after surgery, levels of CTGF protein increased dramatically, slightly after mRNA levels began to increase in the corneas, and continued to increase through day 21 after surgery, reaching approximately fold higher levels than in noninjured corneas.
By day 21, all corneas showed significant corneal haze, corresponding with elevated levels of CTGF.
The fibroblasts in the dermis spend majority of time in quiescent state. However in response to activation, the fibroblasts can be reactivated, and certain pool of cell is able to differentiate into myofibroblasts which have important role in repairing skin defects such as during wound healing.
During aging the number of fibroblasts is markedly reduced.
Also the response of fibroblasts to various growth factors and mechanical or pathological stimulates wound healing is diminished. In aging skin, collagen fibers become thicker and less soluble and the synthesis of collagen declines. Skin thickness remains quite constant between 20 and 70 years of age, after which a marked decrease in skin thickness occurs. During aging the expression of collagenases are increased and inhibitors of collagenases are reduced leading to increased proteolysis of connective tissue.
Recent studies have shown that collagen synthesis is declined in the skin of heavy smokers, while collagenases are increased inducing premature skin aging. The elastic properties of skin are also affected by aging.
Along with increasing age, dermal elastic fibers become thicker and fragmented and oxytalan fibers appear fragmented and shortened. Disintegration of elastic fibers is already seen in a minority of fibers between ages 30 and 70, but the changes become more profound after the age of 70 years, affecting a majority of the fibers.Reticular fibers, the third type of protein fiber found in connective tissues, consist of thin strands of collagen that form a network of fibers to support the tissue and other organs to which it is connected.
The space between the formed elements of the tissue is filled with the matrix. On day 7, numerous fibroblast-like cells and inflammatory cells were present that stained strongly for CTGF. Thank you for submitting a comment on this article. Biglycan and decorin in intact developing tissues: This arrangement, especially when configured as small cylinders, such as in osteons, imparts a great deal of multidirectional tensile strength.
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