Bone Regeneration: Renewal or repair of lost bone tissue. It excludes BONY CALLUS formed after BONE FRACTURES but not yet replaced by hard bone.Regeneration: The physiological renewal, repair, or replacement of tissue.Bone and Bones: A specialized CONNECTIVE TISSUE that is the main constituent of the SKELETON. The principle cellular component of bone is comprised of OSTEOBLASTS; OSTEOCYTES; and OSTEOCLASTS, while FIBRILLAR COLLAGENS and hydroxyapatite crystals form the BONE MATRIX.Guided Tissue Regeneration: Procedures for enhancing and directing tissue repair and renewal processes, such as BONE REGENERATION; NERVE REGENERATION; etc. They involve surgically implanting growth conducive tracks or conduits (TISSUE SCAFFOLDING) at the damaged site to stimulate and control the location of cell repopulation. The tracks or conduits are made from synthetic and/or natural materials and may include support cells and induction factors for CELL GROWTH PROCESSES; or CELL MIGRATION.Bone Substitutes: Synthetic or natural materials for the replacement of bones or bone tissue. They include hard tissue replacement polymers, natural coral, hydroxyapatite, beta-tricalcium phosphate, and various other biomaterials. The bone substitutes as inert materials can be incorporated into surrounding tissue or gradually replaced by original tissue.Osteogenesis: The process of bone formation. Histogenesis of bone including ossification.Nerve Regeneration: Renewal or physiological repair of damaged nerve tissue.Liver Regeneration: Repair or renewal of hepatic tissue.Bone Remodeling: The continuous turnover of BONE MATRIX and mineral that involves first an increase in BONE RESORPTION (osteoclastic activity) and later, reactive BONE FORMATION (osteoblastic activity). The process of bone remodeling takes place in the adult skeleton at discrete foci. The process ensures the mechanical integrity of the skeleton throughout life and plays an important role in calcium HOMEOSTASIS. An imbalance in the regulation of bone remodeling's two contrasting events, bone resorption and bone formation, results in many of the metabolic bone diseases, such as OSTEOPOROSIS.Tissue Scaffolds: Cell growth support structures composed of BIOCOMPATIBLE MATERIALS. They are specially designed solid support matrices for cell attachment in TISSUE ENGINEERING and GUIDED TISSUE REGENERATION uses.X-Ray Microtomography: X-RAY COMPUTERIZED TOMOGRAPHY with resolution in the micrometer range.Calcium Phosphates: Calcium salts of phosphoric acid. These compounds are frequently used as calcium supplements.Bone Morphogenetic Protein 2: A potent osteoinductive protein that plays a critical role in the differentiation of osteoprogenitor cells into OSTEOBLASTS.Skull: The SKELETON of the HEAD including the FACIAL BONES and the bones enclosing the BRAIN.Bone Density: The amount of mineral per square centimeter of BONE. This is the definition used in clinical practice. Actual bone density would be expressed in grams per milliliter. It is most frequently measured by X-RAY ABSORPTIOMETRY or TOMOGRAPHY, X RAY COMPUTED. Bone density is an important predictor for OSTEOPOROSIS.Bone Matrix: Extracellular substance of bone tissue consisting of COLLAGEN fibers, ground substance, and inorganic crystalline minerals and salts.Bone Diseases: Diseases of BONES.Biocompatible Materials: Synthetic or natural materials, other than DRUGS, that are used to replace or repair any body TISSUES or bodily function.Tissue Engineering: Generating tissue in vitro for clinical applications, such as replacing wounded tissues or impaired organs. The use of TISSUE SCAFFOLDING enables the generation of complex multi-layered tissues and tissue structures.Parietal Bone: One of a pair of irregularly shaped quadrilateral bones situated between the FRONTAL BONE and OCCIPITAL BONE, which together form the sides of the CRANIUM.Osteoblasts: Bone-forming cells which secrete an EXTRACELLULAR MATRIX. HYDROXYAPATITE crystals are then deposited into the matrix to form bone.Platelet-Rich Plasma: A preparation consisting of PLATELETS concentrated in a limited volume of PLASMA. This is used in various surgical tissue regeneration procedures where the GROWTH FACTORS in the platelets enhance wound healing and regeneration.Bone Transplantation: The grafting of bone from a donor site to a recipient site.Bone Marrow Cells: Cells contained in the bone marrow including fat cells (see ADIPOCYTES); STROMAL CELLS; MEGAKARYOCYTES; and the immediate precursors of most blood cells.Durapatite: The mineral component of bones and teeth; it has been used therapeutically as a prosthetic aid and in the prevention and treatment of osteoporosis.Bone Development: The growth and development of bones from fetus to adult. It includes two principal mechanisms of bone growth: growth in length of long bones at the epiphyseal cartilages and growth in thickness by depositing new bone (OSTEOGENESIS) with the actions of OSTEOBLASTS and OSTEOCLASTS.Guided Tissue Regeneration, Periodontal: Techniques for enhancing and directing cell growth to repopulate specific parts of the PERIODONTIUM that have been damaged by PERIODONTAL DISEASES; TOOTH DISEASES; or TRAUMA, or to correct TOOTH ABNORMALITIES. Repopulation and repair is achieved by guiding the progenitor cells to reproduce in the desired location by blocking contact with surrounding tissue by use of membranes composed of synthetic or natural material that may include growth inducing factors as well.Absorbable Implants: Implants constructed of materials designed to be absorbed by the body without producing an immune response. They are usually composed of plastics and are frequently used in orthopedics and orthodontics.Bone Resorption: Bone loss due to osteoclastic activity.Implants, Experimental: Artificial substitutes for body parts and materials inserted into organisms during experimental studies.Bone Marrow: The soft tissue filling the cavities of bones. Bone marrow exists in two types, yellow and red. Yellow marrow is found in the large cavities of large bones and consists mostly of fat cells and a few primitive blood cells. Red marrow is a hematopoietic tissue and is the site of production of erythrocytes and granular leukocytes. Bone marrow is made up of a framework of connective tissue containing branching fibers with the frame being filled with marrow cells.Mesenchymal Stromal Cells: Bone-marrow-derived, non-hematopoietic cells that support HEMATOPOETIC STEM CELLS. They have also been isolated from other organs and tissues such as UMBILICAL CORD BLOOD, umbilical vein subendothelium, and WHARTON JELLY. These cells are considered to be a source of multipotent stem cells because they include subpopulations of mesenchymal stem cells.Fracture Healing: The physiological restoration of bone tissue and function after a fracture. It includes BONY CALLUS formation and normal replacement of bone tissue.Bone Morphogenetic Proteins: Bone-growth regulatory factors that are members of the transforming growth factor-beta superfamily of proteins. They are synthesized as large precursor molecules which are cleaved by proteolytic enzymes. The active form can consist of a dimer of two identical proteins or a heterodimer of two related bone morphogenetic proteins.Osseointegration: The growth action of bone tissue as it assimilates surgically implanted devices or prostheses to be used as either replacement parts (e.g., hip) or as anchors (e.g., endosseous dental implants).Calcification, Physiologic: Process by which organic tissue becomes hardened by the physiologic deposit of calcium salts.Mandible: The largest and strongest bone of the FACE constituting the lower jaw. It supports the lower teeth.Femur: The longest and largest bone of the skeleton, it is situated between the hip and the knee.Bone Neoplasms: Tumors or cancer located in bone tissue or specific BONES.Osteogenesis, Distraction: Bone lengthening by gradual mechanical distraction. An external fixation device produces the distraction across the bone plate. The technique was originally applied to long bones but in recent years the method has been adapted for use with mandibular implants in maxillofacial surgery.Cell Differentiation: Progressive restriction of the developmental potential and increasing specialization of function that leads to the formation of specialized cells, tissues, and organs.Wound Healing: Restoration of integrity to traumatized tissue.Periosteum: Thin outer membrane that surrounds a bone. It contains CONNECTIVE TISSUE, CAPILLARIES, nerves, and a number of cell types.Porosity: Condition of having pores or open spaces. This often refers to bones, bone implants, or bone cements, but can refer to the porous state of any solid substance.Alveolar Bone Loss: Resorption or wasting of the tooth-supporting bone (ALVEOLAR PROCESS) in the MAXILLA or MANDIBLE.Alkaline Phosphatase: An enzyme that catalyzes the conversion of an orthophosphoric monoester and water to an alcohol and orthophosphate. EC 3.1.3.1.Nanofibers: Submicron-sized fibers with diameters typically between 50 and 500 nanometers. The very small dimension of these fibers can generate a high surface area to volume ratio, which makes them potential candidates for various biomedical and other applications.Nanocomposites: Nanometer-scale composite structures composed of organic molecules intimately incorporated with inorganic molecules. (Glossary of Biotechnology and Nanobiotechology Terms, 4th ed)Calcium Sulfate: A calcium salt that is used for a variety of purposes including: building materials, as a desiccant, in dentistry as an impression material, cast, or die, and in medicine for immobilizing casts and as a tablet excipient. It exists in various forms and states of hydration. Plaster of Paris is a mixture of powdered and heat-treated gypsum.Bone Morphogenetic Protein 7: A bone morphogenetic protein that is widely expressed during EMBRYONIC DEVELOPMENT. It is both a potent osteogenic factor and a specific regulator of nephrogenesis.Dental Implants: Biocompatible materials placed into (endosseous) or onto (subperiosteal) the jawbone to support a crown, bridge, or artificial tooth, or to stabilize a diseased tooth.Bone Cements: Adhesives used to fix prosthetic devices to bones and to cement bone to bone in difficult fractures. Synthetic resins are commonly used as cements. A mixture of monocalcium phosphate, monohydrate, alpha-tricalcium phosphate, and calcium carbonate with a sodium phosphate solution is also a useful bone paste.Hematocele: Hemorrhage into a canal or cavity of the body, such as the space covered by the serous membrane (tunica vaginalis) around the TESTIS leading to testicular hematocele or scrotal hematocele.Maxillary Sinus: The air space located in the body of the MAXILLARY BONE near each cheek. Each maxillary sinus communicates with the middle passage (meatus) of the NASAL CAVITY on the same side.Ceramics: Products made by baking or firing nonmetallic minerals (clay and similar materials). In making dental restorations or parts of restorations the material is fused porcelain. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed & Boucher's Clinical Dental Terminology, 4th ed)Materials Testing: The testing of materials and devices, especially those used for PROSTHESES AND IMPLANTS; SUTURES; TISSUE ADHESIVES; etc., for hardness, strength, durability, safety, efficacy, and biocompatibility.Skull Fractures: Fractures of the skull which may result from penetrating or nonpenetrating head injuries or rarely BONE DISEASES (see also FRACTURES, SPONTANEOUS). Skull fractures may be classified by location (e.g., SKULL FRACTURE, BASILAR), radiographic appearance (e.g., linear), or based upon cranial integrity (e.g., SKULL FRACTURE, DEPRESSED).Mandibular Injuries: Injuries to the lower jaw bone.Polyglycolic Acid: A biocompatible polymer used as a surgical suture material.Mandibular Osteotomy: Intraoral OSTEOTOMY of the lower jaw usually performed in order to correct MALOCCLUSION.Mandibular Fractures: Fractures of the lower jaw.Bony Callus: The bony deposit formed between and around the broken ends of BONE FRACTURES during normal healing.Gelatin: A product formed from skin, white connective tissue, or bone COLLAGEN. It is used as a protein food adjuvant, plasma substitute, hemostatic, suspending agent in pharmaceutical preparations, and in the manufacturing of capsules and suppositories.Bone Marrow Transplantation: The transference of BONE MARROW from one human or animal to another for a variety of purposes including HEMATOPOIETIC STEM CELL TRANSPLANTATION or MESENCHYMAL STEM CELL TRANSPLANTATION.Fractures, Bone: Breaks in bones.Dental Implantation, Endosseous: Insertion of an implant into the bone of the mandible or maxilla. The implant has an exposed head which protrudes through the mucosa and is a prosthodontic abutment.Core Binding Factor Alpha 1 Subunit: A transcription factor that dimerizes with CORE BINDING FACTOR BETA SUBUNIT to form core binding factor. It contains a highly conserved DNA-binding domain known as the runt domain and is involved in genetic regulation of skeletal development and CELL DIFFERENTIATION.Tibia: The second longest bone of the skeleton. It is located on the medial side of the lower leg, articulating with the FIBULA laterally, the TALUS distally, and the FEMUR proximally.Stem Cells: Relatively undifferentiated cells that retain the ability to divide and proliferate throughout postnatal life to provide progenitor cells that can differentiate into specialized cells.Microscopy, Electron, Scanning: Microscopy in which the object is examined directly by an electron beam scanning the specimen point-by-point. The image is constructed by detecting the products of specimen interactions that are projected above the plane of the sample, such as backscattered electrons. Although SCANNING TRANSMISSION ELECTRON MICROSCOPY also scans the specimen point by point with the electron beam, the image is constructed by detecting the electrons, or their interaction products that are transmitted through the sample plane, so that is a form of TRANSMISSION ELECTRON MICROSCOPY.Mesenchymal Stem Cell Transplantation: Transfer of MESENCHYMAL STEM CELLS between individuals within the same species (TRANSPLANTATION, HOMOLOGOUS) or transfer within the same individual (TRANSPLANTATION, AUTOLOGOUS).Cell Proliferation: All of the processes involved in increasing CELL NUMBER including CELL DIVISION.Alveolar Process: The thickest and spongiest part of the maxilla and mandible hollowed out into deep cavities for the teeth.Apatites: A group of phosphate minerals that includes ten mineral species and has the general formula X5(YO4)3Z, where X is usually calcium or lead, Y is phosphorus or arsenic, and Z is chlorine, fluorine, or OH-. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Silk: A continuous protein fiber consisting primarily of FIBROINS. It is synthesized by a variety of INSECTS and ARACHNIDS.Silicone Elastomers: Polymers of silicone that are formed by crosslinking and treatment with amorphous silica to increase strength. They have properties similar to vulcanized natural rubber, in that they stretch under tension, retract rapidly, and fully recover to their original dimensions upon release. They are used in the encapsulation of surgical membranes and implants.Cells, Cultured: Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.Polyesters: Polymers of organic acids and alcohols, with ester linkages--usually polyethylene terephthalate; can be cured into hard plastic, films or tapes, or fibers which can be woven into fabrics, meshes or velours.Hydrogels: Water swollen, rigid, 3-dimensional network of cross-linked, hydrophilic macromolecules, 20-95% water. They are used in paints, printing inks, foodstuffs, pharmaceuticals, and cosmetics. (Grant & Hackh's Chemical Dictionary, 5th ed)Mandibular Neoplasms: Tumors or cancer of the MANDIBLE.Tooth Socket: A hollow part of the alveolar process of the MAXILLA or MANDIBLE where each tooth fits and is attached via the periodontal ligament.Chitosan: Deacetylated CHITIN, a linear polysaccharide of deacetylated beta-1,4-D-glucosamine. It is used in HYDROGEL and to treat WOUNDS.Ricinus: A plant genus of the family EUPHORBIACEAE, order Euphorbiales, subclass Rosidae. The seed of Ricinus communis L. is the CASTOR BEAN which is the source of CASTOR OIL; RICIN; and other lectins.Dental Implantation: The grafting or inserting of a prosthetic device of alloplastic material into the oral tissue beneath the mucosal or periosteal layer or within the bone. Its purpose is to provide support and retention to a partial or complete denture.Osteocytes: Mature osteoblasts that have become embedded in the BONE MATRIX. They occupy a small cavity, called lacuna, in the matrix and are connected to adjacent osteocytes via protoplasmic projections called canaliculi.Biomimetic Materials: Materials fabricated by BIOMIMETICS techniques, i.e., based on natural processes found in biological systems.Nephroblastoma Overexpressed Protein: A CCN protein family member found at high levels in NEPHROBLASTOMA cells. It is found both intracellularly and in the EXTRACELLULAR MATRIX and may play a role in the regulation of CELL PROLIFERATION and EXTRACELLULAR MATRIX synthesis.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Alginates: Salts of alginic acid that are extracted from marine kelp and used to make dental impressions and as absorbent material for surgical dressings.Membranes, Artificial: Artificially produced membranes, such as semipermeable membranes used in artificial kidney dialysis (RENAL DIALYSIS), monomolecular and bimolecular membranes used as models to simulate biological CELL MEMBRANES. These membranes are also used in the process of GUIDED TISSUE REGENERATION.Planarians: Nonparasitic free-living flatworms of the class Turbellaria. The most common genera are Dugesia, formerly Planaria, which lives in water, and Bipalium, which lives on land. Geoplana occurs in South America and California.Hepatectomy: Excision of all or part of the liver. (Dorland, 28th ed)Titanium: A dark-gray, metallic element of widespread distribution but occurring in small amounts; atomic number, 22; atomic weight, 47.90; symbol, Ti; specific gravity, 4.5; used for fixation of fractures. (Dorland, 28th ed)Femoral Fractures: Fractures of the femur.Models, Animal: Non-human animals, selected because of specific characteristics, for use in experimental research, teaching, or testing.Hydrogel: A network of cross-linked hydrophilic macromolecules used in biomedical applications.Osteocalcin: Vitamin K-dependent calcium-binding protein synthesized by OSTEOBLASTS and found primarily in BONES. Serum osteocalcin measurements provide a noninvasive specific marker of bone metabolism. The protein contains three residues of the amino acid gamma-carboxyglutamic acid (Gla), which, in the presence of CALCIUM, promotes binding to HYDROXYAPATITE and subsequent accumulation in BONE MATRIX.Siloxanes: Silicon polymers that contain alternate silicon and oxygen atoms in linear or cyclic molecular structures.Alveolar Ridge Augmentation: Preprosthetic surgery involving rib, cartilage, or iliac crest bone grafts, usually autologous, or synthetic implants for rebuilding the alveolar ridge.Bone Diseases, MetabolicGlass: Hard, amorphous, brittle, inorganic, usually transparent, polymerous silicate of basic oxides, usually potassium or sodium. It is used in the form of hard sheets, vessels, tubing, fibers, ceramics, beads, etc.Integrin-Binding Sialoprotein: A highly glycosylated and sulfated phosphoprotein that is found almost exclusively in mineralized connective tissues. It is an extracellular matrix protein that binds to hydroxyapatite through polyglutamic acid sequences and mediates cell attachment through an RGD sequence.Mice, Inbred C57BLPolypropylenes: Propylene or propene polymers. Thermoplastics that can be extruded into fibers, films or solid forms. They are used as a copolymer in plastics, especially polyethylene. The fibers are used for fabrics, filters and surgical sutures.Minerals: Native, inorganic or fossilized organic substances having a definite chemical composition and formed by inorganic reactions. They may occur as individual crystals or may be disseminated in some other mineral or rock. (Grant & Hackh's Chemical Dictionary, 5th ed; McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Ameloblastoma: An immature epithelial tumor of the JAW originating from the epithelial rests of Malassez or from other epithelial remnants of the ENAMEL from the developmental period. It is a slowly growing tumor, usually benign, but displays a marked propensity for invasive growth.Axons: Nerve fibers that are capable of rapidly conducting impulses away from the neuron cell body.Periodontal Ligament: The fibrous CONNECTIVE TISSUE surrounding the TOOTH ROOT, separating it from and attaching it to the alveolar bone (ALVEOLAR PROCESS).Compressive Strength: The maximum compression a material can withstand without failure. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 5th ed, p427)Polytetrafluoroethylene: Homopolymer of tetrafluoroethylene. Nonflammable, tough, inert plastic tubing or sheeting; used to line vessels, insulate, protect or lubricate apparatus; also as filter, coating for surgical implants or as prosthetic material. Synonyms: Fluoroflex; Fluoroplast; Ftoroplast; Halon; Polyfene; PTFE; Tetron.Neovascularization, Physiologic: The development of new BLOOD VESSELS during the restoration of BLOOD CIRCULATION during the healing process.Salamandridae: A family of Urodela consisting of 15 living genera and about 42 species and occurring in North America, Europe, Asia, and North Africa.Extremities: The farthest or outermost projections of the body, such as the HAND and FOOT.Coated Materials, Biocompatible: Biocompatible materials usually used in dental and bone implants that enhance biologic fixation, thereby increasing the bond strength between the coated material and bone, and minimize possible biological effects that may result from the implant itself.Disease Models, Animal: Naturally occurring or experimentally induced animal diseases with pathological processes sufficiently similar to those of human diseases. They are used as study models for human diseases.Ambystoma mexicanum: A salamander found in Mexican mountain lakes and accounting for about 30 percent of the urodeles used in research. The axolotl remains in larval form throughout its life, a phenomenon known as neoteny.Collagen Type I: The most common form of fibrillar collagen. It is a major constituent of bone (BONE AND BONES) and SKIN and consists of a heterotrimer of two alpha1(I) and one alpha2(I) chains.Rats, Sprague-Dawley: A strain of albino rat used widely for experimental purposes because of its calmness and ease of handling. It was developed by the Sprague-Dawley Animal Company.Adult Stem Cells: Cells with high proliferative and self renewal capacities derived from adults.Collagen: A polypeptide substance comprising about one third of the total protein in mammalian organisms. It is the main constituent of SKIN; CONNECTIVE TISSUE; and the organic substance of bones (BONE AND BONES) and teeth (TOOTH).Nerve Crush: Treatment of muscles and nerves under pressure as a result of crush injuries.Prostheses and Implants: Artificial substitutes for body parts, and materials inserted into tissue for functional, cosmetic, or therapeutic purposes. Prostheses can be functional, as in the case of artificial arms and legs, or cosmetic, as in the case of an artificial eye. Implants, all surgically inserted or grafted into the body, tend to be used therapeutically. IMPLANTS, EXPERIMENTAL is available for those used experimentally.Rats, Nude: A mutant strain of Rattus norvegicus without a thymus and with depressed or absent T-cell function. This strain of rats may have a small amount of hair at times, but then lose it.Multipotent Stem Cells: Specialized stem cells that are committed to give rise to cells that have a particular function; examples are MYOBLASTS; MYELOID PROGENITOR CELLS; and skin stem cells. (Stem Cells: A Primer [Internet]. Bethesda (MD): National Institutes of Health (US); 2000 May [cited 2002 Apr 5]. Available from: http://www.nih.gov/news/stemcell/primer.htm)Rabbits: The species Oryctolagus cuniculus, in the family Leporidae, order LAGOMORPHA. Rabbits are born in burrows, furless, and with eyes and ears closed. In contrast with HARES, rabbits have 22 chromosome pairs.Polyurethanes: A group of thermoplastic or thermosetting polymers containing polyisocyanate. They are used as ELASTOMERS, as coatings, as fibers and as foams.Immunohistochemistry: Histochemical localization of immunoreactive substances using labeled antibodies as reagents.Smad5 Protein: A receptor-regulated smad protein that undergoes PHOSPHORYLATION by BONE MORPHOGENETIC PROTEIN RECEPTORS. It regulates BONE MORPHOGENETIC PROTEIN signaling and is essential for PHYSIOLOGICAL ANGIOGENESIS.Rats, Wistar: A strain of albino rat developed at the Wistar Institute that has spread widely at other institutions. This has markedly diluted the original strain.Lactic Acid: A normal intermediate in the fermentation (oxidation, metabolism) of sugar. The concentrated form is used internally to prevent gastrointestinal fermentation. (From Stedman, 26th ed)Notophthalmus viridescens: A species of newt in the Salamandridae family in which the larvae transform into terrestrial eft stage and later into an aquatic adult. They occur from Canada to southern United States. Viridescens refers to the greenish color often found in this species.Temporal Bone: Either of a pair of compound bones forming the lateral (left and right) surfaces and base of the skull which contains the organs of hearing. It is a large bone formed by the fusion of parts: the squamous (the flattened anterior-superior part), the tympanic (the curved anterior-inferior part), the mastoid (the irregular posterior portion), and the petrous (the part at the base of the skull).Tooth Extraction: The surgical removal of a tooth. (Dorland, 28th ed)Animal Fins: Membranous appendage of fish and other aquatic organisms used for locomotion or balance.Drug Delivery Systems: Systems for the delivery of drugs to target sites of pharmacological actions. Technologies employed include those concerning drug preparation, route of administration, site targeting, metabolism, and toxicity.Anthraquinones: Compounds based on ANTHRACENES which contain two KETONES in any position. Substitutions can be in any position except on the ketone groups.Biomechanical Phenomena: The properties, processes, and behavior of biological systems under the action of mechanical forces.Craniosynostoses: Premature closure of one or more CRANIAL SUTURES. It often results in plagiocephaly. Craniosynostoses that involve multiple sutures are sometimes associated with congenital syndromes such as ACROCEPHALOSYNDACTYLIA; and CRANIOFACIAL DYSOSTOSIS.Gene Expression Regulation: Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control (induction or repression) of gene action at the level of transcription or translation.Transforming Growth Factor beta: A factor synthesized in a wide variety of tissues. It acts synergistically with TGF-alpha in inducing phenotypic transformation and can also act as a negative autocrine growth factor. TGF-beta has a potential role in embryonal development, cellular differentiation, hormone secretion, and immune function. TGF-beta is found mostly as homodimer forms of separate gene products TGF-beta1, TGF-beta2 or TGF-beta3. Heterodimers composed of TGF-beta1 and 2 (TGF-beta1.2) or of TGF-beta2 and 3 (TGF-beta2.3) have been isolated. The TGF-beta proteins are synthesized as precursor proteins.Umbilical Cord: The flexible rope-like structure that connects a developing FETUS to the PLACENTA in mammals. The cord contains blood vessels which carry oxygen and nutrients from the mother to the fetus and waste products away from the fetus.Hexuronic Acids: Term used to designate tetrahydroxy aldehydic acids obtained by oxidation of hexose sugars, i.e. glucuronic acid, galacturonic acid, etc. Historically, the name hexuronic acid was originally given to ascorbic acid.TailGlucuronic Acid: A sugar acid formed by the oxidation of the C-6 carbon of GLUCOSE. In addition to being a key intermediate metabolite of the uronic acid pathway, glucuronic acid also plays a role in the detoxification of certain drugs and toxins by conjugating with them to form GLUCURONIDES.Rats, Inbred F344Nanostructures: Materials which have structured components with at least one dimension in the range of 1 to 100 nanometers. These include NANOCOMPOSITES; NANOPARTICLES; NANOTUBES; and NANOWIRES.Cell Survival: The span of viability of a cell characterized by the capacity to perform certain functions such as metabolism, growth, reproduction, some form of responsiveness, and adaptability.Satellite Cells, Skeletal Muscle: Elongated, spindle-shaped, quiescent myoblasts lying in close contact with adult skeletal muscle. They are thought to play a role in muscle repair and regeneration.Surface Properties: Characteristics or attributes of the outer boundaries of objects, including molecules.Fumarates: Compounds based on fumaric acid.Spinal Cord Regeneration: Repair of the damaged neuron function after SPINAL CORD INJURY or SPINAL CORD DISEASES.Sciatic Nerve: A nerve which originates in the lumbar and sacral spinal cord (L4 to S3) and supplies motor and sensory innervation to the lower extremity. The sciatic nerve, which is the main continuation of the sacral plexus, is the largest nerve in the body. It has two major branches, the TIBIAL NERVE and the PERONEAL NERVE.Prosthesis Implantation: Surgical insertion of a prosthesis.Elastic Modulus: Numerical expression indicating the measure of stiffness in a material. It is defined by the ratio of stress in a unit area of substance to the resulting deformation (strain). This allows the behavior of a material under load (such as bone) to be calculated.Drug Carriers: Forms to which substances are incorporated to improve the delivery and the effectiveness of drugs. Drug carriers are used in drug-delivery systems such as the controlled-release technology to prolong in vivo drug actions, decrease drug metabolism, and reduce drug toxicity. Carriers are also used in designs to increase the effectiveness of drug delivery to the target sites of pharmacological actions. Liposomes, albumin microspheres, soluble synthetic polymers, DNA complexes, protein-drug conjugates, and carrier erythrocytes among others have been employed as biodegradable drug carriers.Tomography, X-Ray Computed: Tomography using x-ray transmission and a computer algorithm to reconstruct the image.Injections: Introduction of substances into the body using a needle and syringe.Osteoclasts: A large multinuclear cell associated with the BONE RESORPTION. An odontoclast, also called cementoclast, is cytomorphologically the same as an osteoclast and is involved in CEMENTUM resorption.Cell Culture Techniques: Methods for maintaining or growing CELLS in vitro.Osteotomy: The surgical cutting of a bone. (Dorland, 28th ed)Vascular Endothelial Growth Factor A: The original member of the family of endothelial cell growth factors referred to as VASCULAR ENDOTHELIAL GROWTH FACTORS. Vascular endothelial growth factor-A was originally isolated from tumor cells and referred to as "tumor angiogenesis factor" and "vascular permeability factor". Although expressed at high levels in certain tumor-derived cells it is produced by a wide variety of cell types. In addition to stimulating vascular growth and vascular permeability it may play a role in stimulating VASODILATION via NITRIC OXIDE-dependent pathways. Alternative splicing of the mRNA for vascular endothelial growth factor A results in several isoforms of the protein being produced.Recombinant Proteins: Proteins prepared by recombinant DNA technology.Bone Cysts: Benign unilocular lytic areas in the proximal end of a long bone with well defined and narrow endosteal margins. The cysts contain fluid and the cyst walls may contain some giant cells. Bone cysts usually occur in males between the ages 3-15 years.Osteopontin: A negatively-charged extracellular matrix protein that plays a role in the regulation of BONE metabolism and a variety of other biological functions. Cell signaling by osteopontin may occur through a cell adhesion sequence that recognizes INTEGRIN ALPHA-V BETA-3.Osteoporosis: Reduction of bone mass without alteration in the composition of bone, leading to fractures. Primary osteoporosis can be of two major types: postmenopausal osteoporosis (OSTEOPOROSIS, POSTMENOPAUSAL) and age-related or senile osteoporosis.Signal Transduction: The intracellular transfer of information (biological activation/inhibition) through a signal pathway. In each signal transduction system, an activation/inhibition signal from a biologically active molecule (hormone, neurotransmitter) is mediated via the coupling of a receptor/enzyme to a second messenger system or to an ion channel. Signal transduction plays an important role in activating cellular functions, cell differentiation, and cell proliferation. Examples of signal transduction systems are the GAMMA-AMINOBUTYRIC ACID-postsynaptic receptor-calcium ion channel system, the receptor-mediated T-cell activation pathway, and the receptor-mediated activation of phospholipases. Those coupled to membrane depolarization or intracellular release of calcium include the receptor-mediated activation of cytotoxic functions in granulocytes and the synaptic potentiation of protein kinase activation. Some signal transduction pathways may be part of larger signal transduction pathways; for example, protein kinase activation is part of the platelet activation signal pathway.Zebrafish: An exotic species of the family CYPRINIDAE, originally from Asia, that has been introduced in North America. They are used in embryological studies and to study the effects of certain chemicals on development.Drug Implants: Small containers or pellets of a solid drug implanted in the body to achieve sustained release of the drug.Stromal Cells: Connective tissue cells of an organ found in the loose connective tissue. These are most often associated with the uterine mucosa and the ovary as well as the hematopoietic system and elsewhere.Axotomy: Transection or severing of an axon. This type of denervation is used often in experimental studies on neuronal physiology and neuronal death or survival, toward an understanding of nervous system disease.Polymers: Compounds formed by the joining of smaller, usually repeating, units linked by covalent bonds. These compounds often form large macromolecules (e.g., BIOPOLYMERS; PLASTICS).Muscle, Skeletal: A subtype of striated muscle, attached by TENDONS to the SKELETON. Skeletal muscles are innervated and their movement can be consciously controlled. They are also called voluntary muscles.Reverse Transcriptase Polymerase Chain Reaction: A variation of the PCR technique in which cDNA is made from RNA via reverse transcription. The resultant cDNA is then amplified using standard PCR protocols.Staining and Labeling: The marking of biological material with a dye or other reagent for the purpose of identifying and quantitating components of tissues, cells or their extracts.Microspheres: Small uniformly-sized spherical particles, of micrometer dimensions, frequently labeled with radioisotopes or various reagents acting as tags or markers.Regenerative Medicine: A field of medicine concerned with developing and using strategies aimed at repair or replacement of damaged, diseased, or metabolically deficient organs, tissues, and cells via TISSUE ENGINEERING; CELL TRANSPLANTATION; and ARTIFICIAL ORGANS and BIOARTIFICIAL ORGANS and tissues.Liver: A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances.Intercellular Signaling Peptides and Proteins: Regulatory proteins and peptides that are signaling molecules involved in the process of PARACRINE COMMUNICATION. They are generally considered factors that are expressed by one cell and are responded to by receptors on another nearby cell. They are distinguished from HORMONES in that their actions are local rather than distal.Peripheral Nerves: The nerves outside of the brain and spinal cord, including the autonomic, cranial, and spinal nerves. Peripheral nerves contain non-neuronal cells and connective tissue as well as axons. The connective tissue layers include, from the outside to the inside, the epineurium, the perineurium, and the endoneurium.Biological Markers: Measurable and quantifiable biological parameters (e.g., specific enzyme concentration, specific hormone concentration, specific gene phenotype distribution in a population, presence of biological substances) which serve as indices for health- and physiology-related assessments, such as disease risk, psychiatric disorders, environmental exposure and its effects, disease diagnosis, metabolic processes, substance abuse, pregnancy, cell line development, epidemiologic studies, etc.Models, Biological: Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.Gene Expression: The phenotypic manifestation of a gene or genes by the processes of GENETIC TRANSCRIPTION and GENETIC TRANSLATION.Schwann Cells: Neuroglial cells of the peripheral nervous system which form the insulating myelin sheaths of peripheral axons.Smad1 Protein: A receptor-regulated smad protein that undergoes PHOSPHORYLATION by BONE MORPHOGENETIC PROTEIN RECEPTORS. It regulates BONE MORPHOGENETIC PROTEIN signaling and plays an essential role in EMBRYONIC DEVELOPMENT.Extracellular Matrix: A meshwork-like substance found within the extracellular space and in association with the basement membrane of the cell surface. It promotes cellular proliferation and provides a supporting structure to which cells or cell lysates in culture dishes adhere.