1、Connective Tissue Note for next weeks lesson on nervous systemThe main topics of the nervous tissue are:1. Neuron, 2. Synapse, 3. Neuroglia 5. Nerve fiber, 6. Nerve endingPlease choose one topic you are interesting in and present it with PPT in 10-15 minutes. What is connective tissue? features of c

2、onnective tissue1. Fewer cells many kinds nonplarity no basement membrane2. Abundant intercellular matrix3. Rich in BV / nerve fibers Components of loose CTcomponents of CTCells: fibroblast, macrophage, plasma cell, mast cell, adipocyte, WBC, undifferentiated stem cellsECM: Fibers: collagenous F, el

3、astic F, reticular F Ground substance: GAGs, proteoglycans, glycoproteins, tissue fluid Origination : embryonic mesenchyme homogeneous cell population ; spars RF （間充質）（間充質） processes , spindle-like , gap junctions in mesoderm in umbilical cord Extraembryonic Mesoderm Introembryonic Mesoderm day14-16

4、Day 14Mesenchymal cells Hemangioblasts (1) Angioblasts BV (2) Hematopoitic stem cells (1) (2)Cardiac muscleSkeletal muscleUrogenital system Classification of CTCT proper: loose CT (less fibers) dense CT (dense fibers)Special CT: osseous T : calcified bone matrix (solid) cartilage T : chondroitin-ric

5、h marix (hard) blood : fluid matrix lymphatic T: reticular T + Lc reticular T : RC + RF + ground substance adipose T : LCT rich in adipocytes elastic T: LCT rich in elastinMesenchyme: in embyonic stage DCT LCTCartilage and LCT in respiratory tract RT: RC + RF + ground Substance located in L organs,

6、bone marrowHematopoietic tissue - model (red bone marrow) Bone Marrow (RT, hematopoietic T, adipose T) Adipose tissue Loose connective tissue LCT distribution and functionLocated beneath E; Surround small BV, muscle cell/glands sites for rapid diffusion of gases , nutrients, metabolites initial site

7、s for immune reactions(much immune cells in it: eg. laminar propria of digestive tract) LCT in villi & Lc in CTconnective intercellular matrix or ECMfibers collagen fiber elastic fiber reticular fiberground substance glycosaminoglycans (GAGs糖胺聚糖) proteoglycans glycoprotein tissue fluid *Specific

8、 properties in different T.Collagens in section and spread tissue Mesentery spread under polaring microscope bundles of collagen F / thin elastic FCollagen : the most common type in tendon, ligament, capsule, dermis. white when fresh, pink in HE section tends to form big bundles flexible ; high stre

9、ngth EM: contains fibrils (collagen molecules) Collagen molecule: triple helix 3 -chains Collagen typesUp to date: 28 collagens and 42 -chains polymerizing patterns: fibrillar collagen: type I (dermis.) II (cartilage) III (RF) fibril associated: V, XI network (BM) forming: IV transmembrane: XVII mRN

10、A and -chains ( into RER lumen)hydroxylation (Vc dependent/ scorbutus)bind to sugarpolymerizationtransporting vesiclesprocessed in Golgipackaging secreting to cell surface cut the uncoiled partiallyassembly Extracellular eventsSynthesizing cells of collagen EM of fibrils in cross and longitudinal se

11、ctions show regular alternative dark and light bands -cross striations. Elastic fiberHE: light pink Fresh : yellow periphery: microfibrils (fibrillin原纖維蛋白原纖維蛋白) core: depsitions of elastins More strong: resistant to force (up to 6 X steel) elastic: stretch easily (up to 300 x) stable: acid-resistant

12、 Elastic Fiber = elsatin + fibrillinelastin fibrillin elastic membrane elastin only or fibrillin insufficient Elastic membranes in arteries HE stain silver stain medium-sized A large A Reticular fiber (argyrophilic fiber) Type III collagen coated by proteoglycans Inconspicuous in HEaffinitive to sil

13、ver saltForm a delicate supporting structureGround S. in mouse endometrium (EM) ( fills intercellular space) Ground substanceFills the space between cells and fibersAmorphous(LM): colourless and transparentGranular particles (EM) Act as a lubricant and a barrier Aggregated molecles in tissue fluid:

14、1. (multihesive )glycoproteins: FN , LN,TN,OPN 2. GAGs: HA, chondroitin, dermatan, heparin 3. proteoglycans: core protein + GAGs (exp. HA) Multiadhesive Glycoproteins recognition, adhesion, migration, proliferation, differentiation, tissue organizationFN (fibronectin): 20, bind to C,F,BM,HA, interac

15、t with /influence cells (eg. C migrating) LN ( laminin): basic structure of BM LN-R-LN-IV collagenTN (tenascin 生腱蛋白): young tissue; bind to GFs; switched off in mature tissueOPN (osteopontin 骨橋蛋白): links osteoblast to bone surface promotes calcificationFN guides cardiogenic cells migrationAnchoring

16、function of ECM Glycosaminoglycans(GAGs)Made by disaccharides repeating units, unbranched , rich in OH, -SO4 and NH4hyaluronic acid (HA): the longest, 2.5u,(no SO4) free chain (indirectly bind to proteoglycans) chondroitin sulfate A / C dermatan sulfate (chondroitin sulfate B) heparin sulfate bind (

17、covalently) to core proteinsHA passage (vertical): guides proliferated cells migrating vertically to form septumHeart partitioning model: endothelium subendocardium cardiac muscle HA Barrier function of HAPrevents penetration of invading bacteria and other particular substancesHAase hydrolizes HA to

18、 reduce the viscosity of ground substanceHyaluronidase producing bacteria (streptococcus) have great invasive power in tissues cause sepsis and septicemia Proteoglycans aggrecan 聚合蛋白聚糖cartilage versican EGF domain 多能蛋白聚糖 C to C / C to M syndecan 多配體蛋白聚糖 B cell anchoring decorin 核心蛋白聚糖 M of fibroblas

19、t fibril assembly ECM model ECM Functions 1. supply strength 2. facilitate in rapid diffusion 3. anchor cells in it (cell to matrix adhesion) 4. bind GFs 5. influence information transmission (via C-M interactions) 6. regulate cell functions 7. molecular barrier for particles in it 8. guide tissue /

20、 organ formation cells in connective tissue fixed （resident ） cells fibroblast adipocyte undifferentiated messechymal cellwandering cells plasma cell macrophage mast cell leukocytes Fibroblast“Physical scars”: easily activated Fibroblast in scar tissue MacrophageOrigin: derived from monocyteNumber /

21、 Distribution: much in LO, Liver, inflammatory sitesKinds: constitute mononuclear phagocyte system LM : Size / Shape: large irregularCytoplasm: a big acidophilic (small N/P ratio)Nucleus: one small eccentrical kidney-shape EM: Macrophage (EM) -ultrastructures related to its function Pseudopodia / Pr

22、otrusions Developed cytoskeleton Lysosomes primary L. secondary L. (phagolysosome) residual body Phagocytic granule pinocytic vescicle / phagosome Macrophages function1.migration: ameboid movement chemotaxis: attracted by chemotactic factor2.pahgocytosis: recognition, adhesion engulfing, digestion3.

23、secretion : (50 bioactive molecules) TGF- IL-1 Interferon TNF PGF proteinases 4.Immune : initiating; antigen-presentingPlasma cellPlasma cellMast cell Mast cell Location : near small BVGranules: membrane coated, big, abundant, heterogeneous, basophilic, water soluble, metachromatic (metachromasia: c

24、hange color of applied dye)IgE R on membrane Secretions of mast cell vasoactive subtances inflamative mediators in granule (stored, immediate releasing) Histamine, E/N-chemotactors, Heparinout of granule (new synthesized, delayed)Proteases (chymase / tryptase), Leukotriene（白三烯）（白三烯）-C4(SRS), TGF-, ILs, PGd2 Degranul