Term
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Definition
| forms from lateral to spinal cord and gives rise to skeletal muscle, vertebrae, and dermis of the back;mainly the somites |
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Term
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Definition
| forms lateral to the paraxial mesoderm and gives rise to the UG sinus |
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Term
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Definition
| forms most lateral and gives rise to dermis, connective tissue, and cartilage and bone of skeleton |
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Term
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Definition
| gives rise to smooth muscle and cardiac muscle |
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Term
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Definition
| appears at 4 weeks there is a core of mesoderm covered by ectoderm (apical ectodermal ridge); HOX genes determine in where the limb buds develop; ectoderm-mesenchymal interaction with TBX5 (upper limb) TBX4 (lower limb) |
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Term
| epithelial-mesenchymal interactions in limb bud development |
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Definition
| mesoderm first induces the overlying ectoderm and mesoderm secrete FGF and the ectoderm becomes apical ectodermal ridge induced by BMP and MSX2 and without AER the lib will not develop |
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Term
| proximal vs distal polarity |
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Definition
| directed by radical fringe which is expressed in dorsal ectoderm and engrailed which is expressed in ventral ectoderm and represses radical fringe and SER-2 expressed at the boder area |
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Term
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Definition
| after AER is established FGF (4,8) maintains the progress zone of underlying mesoderm and this zone contains proliferating and undifferentiated cells, and as the cells leave the zone they begin to differentiate |
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Term
| zone of polarizing activity |
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Definition
| determines the anteroposterior pattern of digit formation and this region is in posterior limb bud mesoderm and influences the overlying AER and produces retoinic acid which initiates the production of SHH and regulates AP axis |
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Term
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Definition
| regulated by BMPs which induce engrailed1 expression and repressed wnt7a in ventral ectoderm and wnt7a induces LMX1 in the dorsal ectoderm making it dorsal |
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Term
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Definition
| regulates the types and shapes of bone mostly HOXD HOXA clusters the cartilage models begin develop and mesenchymal cells differentiate into osteoblasts regulated by CBFA1/RUNX2; chondrocytes regulated by SOX9 |
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Term
| progression of end limb development |
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Definition
| cell death occurs along AER and ridge divided into five regions and in between these regions where cell death occurs and seperates these regions; at 6 weeks the cartilage models begin to develop |
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Term
| development of skeletal muscle |
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Definition
| wnt from the dorsal spinal cord induces somite to produce myf5 in myotome and aid in formation of back muscles; wnt from body wall ectoderm induces lateral myotome to express myoD for formation of anterior body wall and limb musculature (hypaxial muscles) |
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Term
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Definition
| cells migrate into the limb bud to develop into muscle and nerves that innervate the somite follow the muscles |
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Term
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Definition
| made of neuroepithelium surround a central canal give rise to neuroblasts form a peripheral layer around the neuroepithelial cells called mantel layer will form the gray matter of the central nervous system |
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Term
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Definition
| neuronal processes from the neuroblasts extend peripherallyy from the mantle layer and as become myelinated will form white matter of CNS |
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Term
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Definition
| more dorsally located cells involved with sensory nerve function |
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Term
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Definition
| ventrally placed cells involved with motor function and between alar and basal plates form the intermediate horn which is involved in formation of autonomic NS |
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Term
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Definition
| column of cells located dorsolateral to neural tube divide into segments that correspond to somite from developing paraxial mesoderm and develop into sensory and autonomic neurons and supporting cells of PNS |
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Term
| intramembranous bone formation |
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Definition
| occurs in the flat bones of the skull and face and begins with mesenchymal cells produce fibers constitute a richly vascularized embryonic membrane which bone can develop |
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Term
| osteoblast differentiation |
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Definition
| induced from mesenchymal cells and produce the organic matrix with collagen type I and vasious non-collagenous proteins known as osteoid; once osteoblasts are enclosed in this they are called osteocytes; osteoblasts as mediate the mineralization of osteoid |
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Term
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Definition
| bony tissue form after successive layers of bone tissue are laid down and they enlarge and merge with each other to form spongy or cancellous bone and the undifferentiated cells in spaces between the trabeculae will differentiate into reticular connective tissue and blood forming cells of the marrow cavity |
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Term
| endochonral bone formation |
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Definition
| bones where they are first laid down as hyaline cartilage models |
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Term
| cartilage model formation |
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Definition
| mesenchymal cell aggregate and differentiate into chondroblasts and chondrocytes and chondrocytes will produce ECM to produce hyaline cartilage which will take shape of bone to be formed, surrounded by a perichondrium made up of an outer fibrous layer and an inner cellular layer |
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Term
| bone formation from the cartilage model |
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Definition
| oldest chondrocytes are in the center of the shaft and these cells hypertrophy and produce enzymes that bring about calcification of the matrix and this prevents the diffusion of nutrients and hypertrophic cells undergo apoptosis cells secrete VEGF before dying; the chondrogenic layer of perichondrium becomes more vascularized and cells differentiate into osteblasts and lay down a bony collar around the shaft of the cartilage model to form periosteum and blood vessels penetrate into center of degenerating calcified cartilage called the primary ossification center |
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Term
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Definition
| gradient in the formation and maturation of chondrocytes between diaphysis and epiphysis find zone of resting cartilage (not dividing), zone of proliferation (dividing mitotically and resemble a stack of coins), zone of hypertrophy and maturation (chondrocytes and their lacunae are enlarged), zone of calcification (intracellular matrix is calcified and chondrocytes are dying), zone of ossification (layer where bone matrix is laid down by osteoblast on calcified cartilage |
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Term
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Definition
| grows in length by proliferation of chondrocytes in metaphyseal region and osseous tiddue being laid down on the remnants of cartilage in the zone of ossification and it grows in diameter by resorption of bone on the inner surfaces of marrow cavity and laying down new bown by periosteal tissue and reabsorption is not as rapid |
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Term
| secondary ossification centers |
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Definition
| develop in the epiphysies later in fetal development or after birth very similar to primary ossification center; on articular surfaces no periosteum or perichondrium exists and hyaline cartilage is retained as a covering to underlying bone and as one of the articulating surfaces of the joint |
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Term
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Definition
| new bone can only be laid down by appositional growth; trapped osteocytes must retain caniculi as connections between lacunae and perivascular spaces and for compact bone that exceeds 0.2 to 0.4 mm must have blood vessels running through it and internal surface surrounding the blood vessel represent the wall of the Haversian canal |
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Term
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Definition
| immature bone that does not display an organized lamellar appearance with random interlacing arrangement of collagen fibers and as remodeled osteons replace immature bone at sites of compact bone or more organized lamellar strucutre replaces the traceculae of spongy |
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Term
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Definition
| movable joint contains synovial fluid in a closed cavity consists largely of ground substance in highly polymerized HA contains a few leukocytes, macrophages, and synovial cells; joint capsule consists of inner stratum layer is synovial membrane and fibrous layer and extends from periosteum of one bone of the joint to the periosteum of the other bone |
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Term
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Definition
| attaches to peripheray of articular cartilage, prominent inflodings of the synovial membrane into the joint cavity are called synovial cells, they secrete synovial fluid these can undergo mitosis and completely repair the membrane in case of injury and richly supplied with blood and lymphatic vessels |
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Term
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Definition
| loss of blood supply to the epiphysis after fracture results in death of the affected cartilaginous tissue and failure of epithelial plate to continue growing |
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Term
| degenerative joint disease |
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Definition
| synovial joints undergo degeneration as a consequence of age, overuse and disease and articular cartilage covering the opposing joint surfaces are first parts of synovial joint to show signs of wear this degeneration is nearly irreversible |
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Term
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Definition
| characterized by excessive proliferation of synovial cells, immune cell infiltration as well as cartilage and bone destruction; increased production of potent inflammatory mediators, cytokines calle TNFa, IL1 are greatly enhnached in RA; these work together in the production of collagenases called MMPs can result in excessive collagen degradation and infiltrating macrophages have ability to differentiate into osteoclasts play a role in bone erosion associated with RA |
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Term
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Definition
| disease process that alters the shape and function of a joint with disease progression, loss of joint space, subchondral sclerosis, osteophytes formation, synovial thickening, and proteoglycan depletion from articular cartilage; imbalance of normal synthesis and turnover of cartilage components; decreased concentration and visocisty of synovial fluid aggravating cartilage degradation |
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Term
| inflammation of bone fractures |
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Definition
| shortest of events facilitates removal of necrotic tissue and stimulates repair; hematoma may form from severed blood vessels; release of substances from platelets and necrotic tissue that will promote dialtion and permeability of blood vessels will aid in bringing nurtitive substances and migratory cells into the injured site; platelets release growth factors and fibrin of hematoma serves as a scaffold for migration of cells into the fracture site; macrophages, neutrophils, and lymphocytes enter the injured site and help remove necrotic tissue and uninjured fibroblasts and endothelial cells near the fracture will proliferate and form new matrix and capillaries |
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Term
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Definition
| continued resorption of necrotic tissue along with inflammation only comprise one half of healing time; dead bone taken up by osteoclasts and replacement of new tissue by cellular proliferation and matrix formation; undifferentiated cells in periosteum, endosteum and other sites proliferate to produce CT and cartilage as well as bone; newly formed bone temporarily bridging the fractured gap is trabecular bone some of which will be replaced by dense bone |
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Term
| remodeling of bone fracture |
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Definition
| final stage characterized by replacement of trabecular bone with lamellar bone and with the resorption of unneeded callus and restoration of mechanical stability across the fracture site; if fracture ends are in direct contact with each other a callus will not form and osteons will extend across the fracture line to accelerate the repair process |
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Term
| factors influencing healing process |
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Definition
| severity of the trauma, extent of the surrounding soft tissue injury, and viability of fractured ends, patient age, hormonal effects, infection, mobility across the fracture site and pre-existing bone disease |
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Term
| physical findings with RA |
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Definition
| bone erosion and soft tissue swelling and decreased joint space on xrays; morning stiffness, symmetric problems, rheymatoid nodules and RF; synovial membrane inflammed with neutrophils, macrophages and lymphocytes; deformaties with subluxations and ulnar deviations of digits reflects imbalance of tendonious forces; also see carpal tunnel syndrome; ruptured Bakers cyst (synovial cyst) |
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Term
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Definition
| fibrinoid necrosis with lots of lymphocytes and mononuclear phagocytes |
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Term
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Definition
| early on there is increase of neutrophils in fluid and increase in blood vessel formation and lymphocytes appear in fluid and pannus forms; APC activates T cells which activate B cells and plasma cells form antibodies and cytokines (anti-CCP); macrophages are also activated and secrete cytokines (TNFa, IL-1, and IL-6 and metalloproteases); osteoclasts activated by RANKL on Tcells and principal reason for erosion of bone |
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Term
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Definition
| TNFa blockade works in 2/3 of RA patients (monoclonal antibodies); IL-17 blocking of T cell activation has shown effective, blocking RANKL to inhibit erosion in RA-no effect on inflammation |
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