HISTOLAB - CONNECTIVE TISSUE

• connective tissue - are supporting and binding for all organs which provide general structure, mechanical strength, space filling, and physical and metabolic support for more specialized tissues
•  three structural properties with corresponding construction materials (4 & 5 are for specialized CT)

  1. tensile strength
  2. elasticity
  3. volume
  4. transport
  5. immunity
• Structurally formed by three classes of components

  • cells
  • fibers
  • ground substance
• ground substance - a highly hydrophilic, viscous complex of anionic macromolecules and multi-adhesives glycoproteins that stabilizes the ECM by binding to receptor proteins on the surface of the cell
• hydrophilic - water loving
• extracellular matrix - consist of different combinations of protein and ground substance
• CONNECTIVE TISSUE CELLS

  • mesenchymal cells
  • fibroblasts
• mesenchymal cells - originated from the mesenchyme
• mesenchyme - an embryonic tissue formed by elongated undifferentiated cells
• undifferentiated cells - a cell that has yet to develop into a particular cell variant
• fibroblasts - most common cells in connective tissue
• two stages of fibrobasts

  • active fibroblasts
  • quiescent fibroblasts (fibrocyte)
• collagen fibers - most abundant and highly tensile strength
• elastic fibers - flexibility /recoil properties
• reticular fibers - consist mainly of collagen type III, which forms extensive networks of extremely thin and heavily glycosylated fibers in certain organs
• spleen - production of platelets
• more platelets - enlarged spleen (splenomegaly)
• ground substance - shapeless background against which cells and collagen fibers are seen in the light microscope
• glycosaminoglycans(GAGs) - also known as Mucopolysaccharides
• proteoglycans - composed of core protein covalently attached to various combinations of GAGs
• glycoproteins - have carbohydrates attached with predominant protein moiety
• areolar - air or air pockets
• loose connective tissue - very common type of CT that supports many structures subjected to some pressure and low friction
• loose connective tissue - areolar tissue
• fibroblasts - responsible for the production of the fibers of the matrix
• under loose connective tissue

  Specimen: esophagus or urinary bladder

  
• dense connective tissue - has extracellular matrix that consists of densely packed fibers
• dense connective tissue - adapted to offer resistance and protection
• regular - one direction

  irregular - multiple directions
• 4 Major Subcategories of Dense Connective Tissue

  1. dense regular collagenous connective tissue
  2. dense irregular collagenous connective tissue
  3. dense regular elastic connective tissue
  4. dense irregular elastic connective tissue
• dense regular collagenous connective tissue - has extracellular matrix consisting mostly of collagen fibers, oriented predominantly in one direction
• dense irregular collagenous connective tissue - composed of collagen fibers that run in all-directions or in alternating planes of fibers oriented in a somewhat single directions
• dense regular elastic connective tissue - consists of parallel bundles of collagen fibers and abundant elastic fibers
• dense irregular elastic connective tissue - composed of bundles and sheets of collagenous and abundant elastic fibers oriented in multiple directions, capable of strength with stretching and recoil in several directions
• reticular connective tissue - specialized CT consists of reticular fibers of type III collagen produced by specialized fibroblasts (reticular cells), creates a sponge-like structure within cells and fluids are freely mobile
• mucous connective tissue - found mainly in the umbilical cord and fetal tissues, abundance of ground substance composed mainly of hyaluronic acid — making it jelly like tissue containing very few collagen fibers with scattered fibroblast
• principal component of umbilical cord - wharton's jelly
• Specimen: umbilical cord

  
• Specimen: embryo, tunica propria of the uterus

  
• adipose connective tissue - main role is to serve as an energy storing reservoir, but it also insulates the body from extreme temperatures, cushions vital organs, and secretes hormones and biological factors