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Tooth Enamel
Tooth enamel is one of the four major tissues that make up the tooth in humans and many other animals, including some species of fish. It makes up the normally visible part of the tooth, covering the crown. The other major tissues are dentin, cementum, and dental pulp. It is a very hard, white to off-white, highly mineralised substance that acts as a barrier to protect the tooth but can become susceptible to degradation, especially by acids from food and drink. Calcium hardens the tooth enamel. In rare circumstances enamel fails to form, leaving the underlying dentin exposed on the surface. Features Enamel is the hardest substance in the human body and contains the highest percentage of minerals (at 96%),Ross ''et al.'', p. 485 with water and organic material composing the rest.Ten Cate's Oral Histology, Nancy, Elsevier, pp. 70–94 The primary mineral is hydroxyapatite, which is a crystalline calcium phosphate. Enamel is formed on the tooth while the tooth develops withi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blausen 0863 ToothAnatomy 02
Blausen Medical Communications, Inc. is the creator and owner of a library of two- and three-dimensional medical and scientific images and animations, a developer of information technology allowing access to that content, and a business focused on licensing and distributing the content. It was founded by Bruce Blausen in Houston, Texas, in 1991, and is privately held. Background Blausen Medical Communications, Inc. (BMC) is a privately held company founded by Bruce Blausen in Houston, Texas in 1991. BMC created and owns a library of medical and scientific images and animations, and has developed information technology Information technology (IT) is the use of computers to create, process, store, retrieve, and exchange all kinds of data . and information. IT forms part of information and communications technology (ICT). An information technology syste ... tools allowing access to the library; as well, it licenses and otherwise works to distribute the content. As o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Human Physical Appearance
Human physical appearance is the outward phenotype or look of human beings. There are infinite variations in human phenotypes, though society reduces the variability to distinct categories. The physical appearance of humans, in particular those attributes which regarded as important for physical attractiveness, are believed by anthropologists to affect the development of personality significantly and social relations. Humans are acutely sensitive to their physical appearance. Some differences in human appearance are genetics, genetic, others are the result of senescence, age, Lifestyle (sociology), lifestyle or disease, and many are the result of personal adornment. Some people have linked some differences with Race (classification of human beings), ethnicity, such as skeletal shape, prognathism or elongated stride. Different cultures place different degrees of emphasis on physical appearance and its importance to social status and other phenomena. Aspects Various aspects are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tomes' Process
Tomes's processes (also called Tomes processes) are a histologic landmark identified on an ameloblast, cells involved in the production of tooth enamel. During the synthesis of enamel, the ameloblast moves away from the enamel, forming a projection surrounded by the developing enamel. Tomes's processes are those projections and give the ameloblast a "picket-fence" appearance under a microscope. They are located on the secretory, basal, end of the ameloblast. Terminal bar apparatuses connect the Tomes's processes. Tonofilaments separate the developing enamel from the enamel organ. Gap junctions synchronize cell activation. The body of the cell between the processes first deposits enamel, which will become the periphery of the enamel prisms, then the Tomes's process will infill the main body of the enamel prism. More than one ameloblast contributes to a single prism. Tomes's processes are distinctly different from Tomes's fibers, which are odontoblastic processes that occupy de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ameloblast
Ameloblasts are cells present only during tooth development that deposit tooth enamel, which is the hard outermost layer of the tooth forming the surface of the crown. Structure Each ameloblast is a columnar cell approximately 4 micrometers in diameter, 40 micrometers in length and is hexagonal in cross section. The secretory end of the ameloblast ends in a six-sided pyramid-like projection known as the Tomes' process. The angulation of the Tomes' process is significant in the orientation of enamel rods, the basic unit of tooth enamel. Distal terminal bars are junctional complexes that separate the Tomes' processes from ameloblast proper. Development Ameloblasts are derived from oral epithelium tissue of ectodermal origin. Their differentiation from preameloblasts (whose origin is from inner enamel epithelium) is a result of signaling from the ectomesenchymal cells of the dental papilla. Initially the preameloblasts will differentiate into presecretory ameloblasts and then in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Micrometre
The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is a unit of length in the International System of Units (SI) equalling (SI standard prefix "micro-" = ); that is, one millionth of a metre (or one thousandth of a millimetre, , or about ). The nearest smaller common SI unit is the nanometre, equivalent to one thousandth of a micrometre, one millionth of a millimetre or one billionth of a metre (). The micrometre is a common unit of measurement for wavelengths of infrared radiation as well as sizes of biological cells and bacteria, and for grading wool by the diameter of the fibres. The width of a single human hair ranges from approximately 20 to . The longest human chromosome, chromosome 1, is approximately in length. Examples Between 1 μm and 10 μm: * 1–10 μm – length of a typical bacterium * 3–8 μm – width of st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enamel Rod
An enamel prism, or enamel rod, is the basic unit of tooth enamel. Measuring 3-6 μm in diameter, enamel prism are tightly packed hydroxyapatite crystals structures. The hydroxyapatite crystals are hexagonal in shape, providing rigidity to the prism and strengthening the enamel. In cross-section, it is best compared to a complex “keyhole” or a “fish-like” shape. The head, which is called the prism core, is oriented toward the tooth’s crown; The tail, which is called the prism sheath, is oriented toward the tooth cervical margin /sup>. The prism core has tightly packed hydroxyapatite crystals. On the other hand, the prism sheath has its crystals less tightly packed and has more space for organic components. These prism structures can usually be visualised within ground sections and/or with the use of a scanning electron microscope on enamel that has been acid etched .html" ;"title="/sup>">/sup>. The number of enamel prisms range approximately from 5 million to 12 mi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enamelin
Enamelin is an enamel matrix protein (EMPs), that in humans is encoded by the ''ENAM'' gene. It is part of the non- amelogenins, which comprise 10% of the total enamel matrix proteins. It is one of the key proteins thought to be involved in amelogenesis (enamel development). The formation of enamel's intricate architecture is thought to be rigorously controlled in ameloblasts through interactions of various organic matrix protein molecules that include: enamelin, amelogenin, ameloblastin, tuftelin, dentine sialophosphoprotein, and a variety of enzymes. Enamelin is the largest protein (~168kDa) in the enamel matrix of developing teeth and is the least abundant (encompasses approximately 1-5%) of total enamel matrix proteins. It is present predominantly at the growing enamel surface. Structure Enamelin is thought to be the oldest member of the enamel matrix protein (EMP) family, with animal studies showing remarkable conservation of the gene phylogenetically. All other EMPs a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amelogenin
Amelogenins are a group of protein isoforms produced by alternative splicing or proteolysis from the ''AMELX'' gene, on the X chromosome, and also the ''AMELY'' gene in males, on the Y chromosome. They are involved in amelogenesis, the development of enamel. Amelogenins are type of extracellular matrix protein, which, together with ameloblastins, enamelins and tuftelins, direct the mineralization of enamel to form a highly organized matrix of rods, interrod crystal and proteins. Although the precise role of amelogenin(s) in regulating the mineralization process is unknown, it is known that amelogenins are abundant during amelogenesis. Developing human enamel contains about 70% protein, 90% of which are amelogenins. Function Amelogenins are believed to be involved in the organizing of enamel rods during tooth development. The latest research indicates that these proteins regulate the initiation and growth of hydroxyapatite crystals during the mineralization of enamel. In a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, responding to stimuli, providing structure to cells and organisms, and transporting molecules from one location to another. Proteins differ from one another primarily in their sequence of amino acids, which is dictated by the nucleotide sequence of their genes, and which usually results in protein folding into a specific 3D structure that determines its activity. A linear chain of amino acid residues is called a polypeptide. A protein contains at least one long polypeptide. Short polypeptides, containing less than 20–30 residues, are rarely considered to be proteins and are commonly called peptides. The individual amino acid residues are bonded together by peptide bonds and adjacent amino acid residues. The sequence of amino acid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bone
A bone is a rigid organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red and white blood cells, store minerals, provide structure and support for the body, and enable mobility. Bones come in a variety of shapes and sizes and have complex internal and external structures. They are lightweight yet strong and hard and serve multiple functions. Bone tissue (osseous tissue), which is also called bone in the uncountable sense of that word, is hard tissue, a type of specialized connective tissue. It has a honeycomb-like matrix internally, which helps to give the bone rigidity. Bone tissue is made up of different types of bone cells. Osteoblasts and osteocytes are involved in the formation and mineralization of bone; osteoclasts are involved in the resorption of bone tissue. Modified (flattened) osteoblasts become the lining cells that form a protective layer on the bone surface. The mineralize ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Collagen
Collagen () is the main structural protein in the extracellular matrix found in the body's various connective tissues. As the main component of connective tissue, it is the most abundant protein in mammals, making up from 25% to 35% of the whole-body protein content. Collagen consists of amino acids bound together to form a triple helix of elongated fibril known as a collagen helix. It is mostly found in connective tissue such as cartilage, bones, tendons, ligaments, and skin. Depending upon the degree of mineralization, collagen tissues may be rigid (bone) or compliant (tendon) or have a gradient from rigid to compliant (cartilage). Collagen is also abundant in corneas, blood vessels, the gut, intervertebral discs, and the dentin in teeth. In muscle tissue, it serves as a major component of the endomysium. Collagen constitutes one to two percent of muscle tissue and accounts for 6% of the weight of the skeletal muscle tissue. The fibroblast is the most common ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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