Introduction to Biomedical Sciences: Connective Tissue (PDF)

Introduction to Biomedical Sciences Connective tissue (1) Prof. D. Dina Helmy Issue 1/ 2018 Code: SOM1-1 Issue 1/ 2018 Code: SOM1-1 Issue 1/ 2018 Code: SOM1-1 Issue 1/ 2018 Code: SOM1-1 Cod...

Introduction to Biomedical Sciences Connective tissue (1) Prof. D. Dina Helmy Issue 1/ 2018 Code: SOM1-1 Issue 1/ 2018 Code: SOM1-1 Issue 1/ 2018 Code: SOM1-1 Issue 1/ 2018 Code: SOM1-1 Code of conduct Effective interaction Switch off Mutual mobile respect phones Smile Appreciate Struggle to our be on time differences Focus on topic Issue 1/ 2018 Code: SOM1-1 Intended learning outcomes By the end of the lecture, the students will be able to: List general characteristics of connective tissue (CT) Name the types of CT. Classify cells (fixed and free) of CT proper Describe the LM, EM and functions of fixed cells of CT proper Issue 1/ 2018 1 Code: SOM1-1  Content General characteristics of connective tissue Classify of cells of CT proper Fixed cells of CT proper: 1-Mesenchymal cells. 2- Pericytes 3- Fibroblasts. 4- Fat cells 5- Fixed macrophages. 6- Reticular cells Issue 1/ 2018 2 Code: SOM1-1  CONNECTIVE TISSUE Issue 1/ 2018 1 Code: SOM1-1 General characteristics of CT: 1- Connects, supports & protects tissues. 2- Mesodermal in origin. 3- Widely separated cells. 4- Formed of cells, fibers & matrix. 5- Penetrated by blood & lymph vessels & nerves. 6- According to matrix consistency: Connective tissue proper (soft), cartilage (rubbery), bone (hard) or blood (fluid). Code: SOM1-1  1. Connective tissue proper Cells Fibres Matrix Code: SOM1-1  I- Connective tissue cells Fixed cells Free cells Components of CT Immune cells 1- Mesenchymal cells. 1- Plasma cells. 2- Pericytes 2- Mast cells. 3- Fibroblasts. 3- Free macrophages 4- Fat cells 4- Leucocytes. 5- Fixed macrophages. 6- Reticular cells Code: SOM1-1  Fixed cells 1- Undifferentiated Mesenchymal cells (UMC) LM: Small branched cell with pale basophilic cytoplasm and oval nucleus. EM: Ribosomes and few organelles. Code: SOM1-1  UMCs Function: -In embryo: stem cells -In adult can differentiate into: Other CT cells Blood cells. Smooth muscles Endothelial cells. Code: SOM1-1  2- Pericyte: -Around blood capillaries. -Branched with long processes. Code: SOM1-1  Pericyte EM: Actin & myosin filaments. Ribosomes & few organelles. Function: Contraction of capillaries. In injury: → - Smooth muscle - Endothelium. - Fibroblasts. Code: SOM1-1  3- Reticular cell: Small branched cell with long branched and anastomosing processes. Central rounded nucleus Function: Secrete reticular fibres. Supportive in stroma of organs. Code: SOM1-1  4- Fibroblasts & fibrocytes: - Most common type*. LM: - Branched with deep basophilic cytoplasm, oval pale nucleus & prominent nucleolus. Code: SOM1-1  Fibroblasts EM: (protein forming) Euchromatic nucleus. Well- developed rER, Golgi & mitochondria Functions: Formation of fibres & matrix. Help in growth & healing. Code: SOM1-1 Fibrocyte: (older fibroblast) - Mature fibroblast. - Fusiform with pale basophilic cytoplasm & dark nucleus. Function: - Maintenance of CT - Healing → Re-activated. Code: SOM1-1  5- Fat (adipose) cells (adipocyte): a- Unilocular fat cells b- Multilocular fat cells Single large droplet of fat Multiple small droplets of fat Code: SOM1-1  a. Unilocular fat cells: - Oval with flat peripheral nucleus & large single central droplet of fat → dissolved → signet ring (with H & E). -Stained with Sudan III (orange). Code: SOM1-1  Unilocular fat cells EM: - ↑ SER & ↓ mitochondria. Function: Storage of fat. Heat insulation. Support some organs. Secrete Leptin → ↓ food intake ↑ metabolism Code: SOM1-1  b. Multilocular fat cells: - Rounded with rounded nucleus & multiple small droplets of fat. - Pigmented. EM: - ↑ mitochondria & ↓SER. Function: - Heat generation → thermogenin (in mitochondria) Code: SOM1-1  Macrophages: LM: - Irregular with pale basophilic granular cytoplasm & eccentric kidney-shaped nucleus. -Vital stain → trypan blue or India ink Code: SOM1-1  Macrophages: EM: - Pseudopodia - ↑ lysosomes & phagocytosed particles (phagosomes). - Well-developed Golgi & rER. Code: SOM1-1  Macrophages: Function: Phagocytosis of micro-organisms. Destruction of old RBCs. Formation of giant cells. Antigen presenting. Code: SOM1-1  Connective tissue: supports and connects other tissues. It is formed of cells, fibres & matrix. Types: CT proper, cartilage, bone & blood. Cells of CT proper: fixed or free. Fixed cells include: UMCs & pericyte (stem cells), fibroblasts & reticular cells (fibres forming), fat cells (fat storing) and macrophages (phagocytic). Issue 1/ 2018 5 Code: SOM1-1 Issue 1/ 2018 Code: SOM1-1 Test your knowledge Mention 1 histological feature & 1 function for each of the following CT cells: 1. fibroblast 2. Unilocular fat cell 3. Macrophage 4. Pericyte Issue 1/ 2018 6 Code: SOM1-1 Issue 1/ 2018 Code: SOM1-1 References Junqueira’s Basic Histology Text & Atlas Wheater's Functional Histology: A Text and Colour Atlas. www.histology-world.com www.bluehistology.com www.lumen.com Issue 1/ 2018 1 Code: SOM1-1 Issue 1/ 2018 Code: SOM1-1