CONNECTIVE TISSUE

1. CONNECTIVE TISSUE Without it you’d fall apart.

2. INTRODUCTION TO CONNECTIVE TISSUE Connective tissue-a tissue, the major constituent of which is extracellular matrix - material between the cells, General: ground substance- matrix found between cells of loose and dense connective tissue Specific types: osteoid matrix-over 90% collagen type I embedded in a ground substance of proteoglycans, condroitin, keratan and hyaluronic acid. Mineralized with calcium phosphate as hydroxyapatite [Ca5(PO4)3(OH)] chondroid matrix - extracellular material between cartliage cells. plasma - the fluid component of blood.

3. EXTRACELLULAR MATRIX OF CONNECTIVE TISSUE The following molecules are found in the extracellular matrix of all types of connective tissue and are major components of the organic matrix of cartilage and bone, 1. glycosaminoglycans- polysaccharides formed of repeating disaccharide sub-units composed of uronic acid and hexosamine •Uronic acidis a hexose with the primary hydroxyl group oxidized to form an acid. •Hexosamineis a hexose with an amino acid attached. Except for hyaluronic acid, glycosaminoglycans are bound to a protein core to form proteoglycan molecules. In combination with hyaluronic acid, proteoglycans can form even larger molecules called proteoglycan aggregates. In all of the above molecules, carbohydrate is the predominant molecular component.

4. Uronic acid Hexosamine Disaccharide subunit Hyaluronic acid

5. EXTRACELLULAR MATRIX OF CONNECTIVE TISSUE 2. glycoproteins- proteins with sugars attached where. The protein forms the major part of the molecule Glycoproteins 10,000 - 700,000 Dalton - a mass unit that is used when describing the molecular weight of large molecules such as proteins and proteoglycans. It is essentially equal to the mass of a hydrogen atom (precisely 1.0000 on the atomic mass scale, a hydrogen atom actually weighs a tad more)."

6. PROTEINECEOUS FIBERS FOUND IN CONNECTIVE TISSUE •Most abundant protein in human body. Molecules of fibers are often oriented to form a sort of lattice. As a result these fibers are birefringent. Various proteineceous fibers are found within the extracellular matrix of glyoproteins, glycosaminoglycans, and proteoglycans. These include, •They are inelastic, but have great tensile strength. Thus can be bent without breaking. 1. Collagen fibers •Impart strength and flexibility to tissue. •Collagen fibers often organized in a parallel array forming a bundle. •There are 5 types of collagen,

7. Types of collagen •Type I - most common, found in every connective tissue. Forms tendons and ligaments microfibrils http://anatgw.tiho-hannover.de/conntis/pcd_imgs/img0011.jpg http://anatgw.tiho-hannover.de/conntis/ko1_bdgw.htm#TYP1 http://www.unomaha.edu/~swick/2740connectivetissue.html http://anatgw.tiho-hannover.de/conntis/pcd_imgs/img0048.jpg

8. Types of collagen •Type II - found in hyaline and elastic cartilage and in the vitreous body of eye. •Type III - found in reticular fibers - healing wounds, smooth muscle, fetal skin, support for cellular structure of some organs such as the liver and spleen •Type IV - found in the basal lamina of epithelia •Type V - found in placental basal laminae, tendon, and muscle sheaths.

9. PROTEINECEOUS FIBERS FOUND IN CONNECTIVE TISSUE a. Form network of fibers. b. Stained black by silver salts (agyrophilic). 2. Reticular fibers c. High glycoprotein content making them PAS-positive. d. Contain collagen type III associated with glycoproteins, proteoglycans and other types of collagen. e. Abundant in smooth muscle and tissues of hematopoietic organs. f. Form a flexible network that strengthens the tissue structure of these organs and supports the cells within. http://www.unomaha.edu/~swick/2740connectivetissue.html

10. Scanning EM - capillary Reticular fibers are important in anchoring small blood vessels to surrounding tissue. C - type I collagen fibers RF - reticular fibers, type III http://education.vetmed.vt.edu/Curriculum/VM8054/Labs/Lab5/Examples/exretic.htm

11. Reticular fibers - type III collagen Here “a whole-mount of a small blood vessel has been stained with silver. The thin black vertical lines are reticular fibers running around the outside of the vessel like barrel hoops. The irregular horizontal lines, running parallel to the length of the vessel are the silvered outlines of endothelial cells.” http://www.meddean.luc.edu/lumen/MedEd/Histo/frames/Histo02.html

12. Reticular fibers - type III collagen “Silver stained smooth muscle of the intestinal wall. Top - inner circular layer, Bottom - outer longitudinal layer. Reticular fibers stain black with a silver stain.” http://www.vh.org/adult/provider/anatomy/MicroscopicAnatomy/Section03/Plate0338.html

13. 2. Elastic fibers •Form - broad, often wavy, diffusely stained bundles. •These bundles branch and fuse with one and other to form network. •Characteristically yellow in living tissue. •The protein elastin is an important component - responsible for elasticity and yellow color. •Stretch to 1 1/2 times unstretched length. http://www.bu.edu/histology/p/00801ooa.htm http://www.siumed.edu/~dking2/intro/ct.htm#elastin http://casweb.cas.ou.edu/pbell/Histology/Captions/Connective/2.areolar.html

14. TYPES OF CELLS FOUND IN CONNECTIVE TISSUES •Flattened, ovoid or stellate cells that have long, tapering, branching processes. 1. Fibroblasts •Actively involved in secretion of extracellular matrix (ground substance) and in fiber formation, usually collagen. •Associated with most connective tissues. •Involved in wound healing, if absent, wound will not heal. •Grow easily in tissue culture (too easily). http://images.google.com/imgres?imgurl=http://www.mediastorehouse.com/image/fibroblast-cells_1698357.jpg&imgrefurl=http://www.mediastorehouse.com/pictures_1698357/fibroblast-cells.html&usg=__8YkQowrFHt87N-HNrgZwbd9ZN8A=&h=447&w=450&sz=122&hl=en&start=41&um=1&tbnid=ZT6NciXUY9evTM:&tbnh=126&tbnw=127&prev=/images%3Fq%3Dfibroblast%2Bpicture%26ndsp%3D21%26hl%3Den%26client%3Dsafari%26rls%3Den%26sa%3DN%26start%3D21%26um%3D1 http://anatgw.tiho-hannover.de/conntis/ko1_bdgw.htm#FIBROGENESE

15. Fibroblasts Rough ER for protein synthesis http://www.meddean.luc.edu/lumen/MedEd/Histo/frames/h_frame4.html

16. 2. Macrophages- many are present in loose connective tissue. Sometimes look similar to fibroblasts; however, they are actively phagocytic. May be fixed in position (histocytes, phagocytes) or wandering (this is usually what we think of as a macrophage). Macrophages are derived from monocytes (white blood cells). Distributed throughout body. Loose (areolar) connective tissue •Magenta arrow - fibroblasts •Green arrow - macrophages •Blue arrow - collagen fiber •Red/orange arrow - elastic fiber http://www.faculty.une.edu/com/abell/histo/histolab2.htm http://www.aids-info.ch/e_te/aas-e-imm.htm

17. 3. Mesenchymal cells •Form embryonic connective tissue cells. •Resemble fibroblasts, but usually smaller, may have stellate appearance. •In adults (as well as children) they are often found aggregated along capillaries where they are called pericytes (or perivascular cells). Differentiate to form new blood vessels and connective tissue after injury. •May differentiate into a number of connective tissue cell types when stimulated by an appropriate inducing factor. http://www.lumen.luc.edu/lumen/meded/Histo/HistoImages/hl2-01.jpg

18. 4. Reticular cells •Cellular network called a cellular reticulum - forms the supportive framework for bone marrow, lymph nodes and the spleen. •Form three-dimensional networks of cells that are in contact via long processes. •May be phagocytic. •Form reticular fibers (type III collagen). Reticulum of lymph node •Also may have a hemopoietic function as precursors for blood stem cells. •Function in immune response. http://www.meddean.luc.edu/lumen/MedEd/Histo/frames/h_fram12.html

19. 5. Mast cells - contain large basophilic granules that are composed of a sulfated glycosaminoglycan called heparin (anticoagulant), as well as other pharmacological agents such as histamine (vasodilator). Important in allergic reactions. 6. Plasma cells - antibody producing B-lymphocytes. Other non-activated B-lymphocytes, as well as T-lymphocytes may also be present in loose C.T. Identifying features - spoke-like arrangement of the chromatin within the nucleus, in the case of plasma cells, a “large” amount of cytoplasm associated with nucleus. http://www.meddean.luc.edu/lumen/MedEd/Histo/frames/h_frame4.html http://www.meddean.luc.edu/lumen/MedEd/Histo/frames/h_frame4.html

20. 7. Adipose cells - unilocular (white), multilocular ( brown) - lipid storage 8. Leukocytes - white blood cells. 9. Pigment cells (melanocytes) - have shape similar to fibroblasts, but cytoplasm contains melanin granules. Originate from neural crest cells in embryo. http://www.unomaha.edu/~swick/2740connectivetissue.html http://www.lab.anhb.uwa.edu.au/mb140/CorePages/Blood/Blood.htm#Neutrophilic http://education.vetmed.vt.edu/Curriculum/VM8054/Labs/Lab14/EXAMPLES/Exmelano.htm

21. TYPES OF CONNECTIVE TISSUE •Delicate, flexible, not very resistant to stress, well vascularized. •All types of connective tissue cells may be present. 1. Loose or areolar connective tissue- •Majority are fibroblasts; however many macrophages and/or lymphocytes may be present. •Collagen, elastic, and reticular fibers present. Relatively many cells and “few” fibers in substantial ground substance. http://www.drbio.cornell.edu/Infrastructure/MPM_WWW/MPM_hist/loose.htm

22. TYPES OF CONNECTIVE TISSUE 2. Dense connective tissue- Clear predominance of collagen fibers at expense of ground substance. Fewer cells than loose connective tissue. Less flexible and more resistant to stress. •When cells and collagen fibers are oriented in a parallel array - dense regular connective tissue. Relatively few cells and many fibers in little ground substance. •When collagen bundles are present without apparent orientation, called dense irregular connectivetissue. http://www.unomaha.edu/~swick/2740connectivetissue.html http://www.pathguy.com/histo/052.htm

23. TYPES OF CONNECTIVE TISSUE 3. Elastic tissue - bundles of thick, parallel elastic fibers. Small amount of loose connective tissue around each bundle. Yellow color. Elastic connective tissue - aorta Reticular connective tissue - spleen elastic fibers - elastin reticular fibers - Type III collagen 4. Reticular tissue - a specialized loose connective tissue with reticular cells that form a fine matrix of reticular fibers. Provides a structural framework for hematopoietic organs such as bone marrow and spleen. http://www.unomaha.edu/~swick/2740connectivetissue.html

24. TYPES OF CONNECTIVE TISSUE 5. Mucous tissue - a lot of amorphous ground substance composed mainly of hyaluronic acid (glycosaminoglycan). Forms a jellylike tissue. Mainly fibroblasts present. Found in umbilical cord (Wharton’s jelly) and pulp of young teeth. Umbilical cord Dental pulp http://anatgw.tiho-hannover.de/conntis/gal_bdgw.htm http://www.kumc.edu/instruction/medicine/anatomy/histoweb/ct/ct15.htm

25. TYPES OF CONNECTIVE TISSUE 6. Adipose tissue- •Specialized for lipid synthesis and storage. •As lipid accumulates, these cells retract their cytoplasmic processes and become spherical. Two types of adipose tissue. •White adipose tissue- adult adipose tissue. Composed of adipose cells, each with a single large droplet (unilocular) of lipid (mostly triglyceride). http://www.unomaha.edu/~swick/2740connectivetissue.html

26. •Contain lipochrome pigments - gives living tissue a brown hue. TYPES OF CONNECTIVE TISSUE •Widespread in fetus and young child. Brown adipose tissue •Each cell contains multiple droplets of lipid (multilocular). •In adults localized in small areas, abundant in animals that hibernate. •Important in heat production for fetus, young child, hibernating animals. http://www.vivo.colostate.edu/hbooks/pathphys/misc_topics/brownfat.html http://anatgw.tiho-hannover.de/bdgw/pcd_imgs/img0074.jpg

27. TYPES OF CONNECTIVE TISSUE •Bone - discussed in next lecture. •Cartilage - discussed in next lecture