Connective Tissue III (I&II) Fall 2021-2022 PDF

Histology MSK101-1 Department CONNECTIVE TISSUE (I&II) By Prof. Sahar Abo Elfadl Prof. of Medical Histology & Cell Biology  Histology...

Histology MSK101-1 Department CONNECTIVE TISSUE (I&II) By Prof. Sahar Abo Elfadl Prof. of Medical Histology & Cell Biology  Histology OBJECTIVES MSK101-1 Department By the end of this lecture you should be able to: List the general characteristics & functions of C.T. Identify the components of C.T. Differentiate between the various types of fixed C.T. cells structurally and functionally. Recognize some related clinical applications.  Histology MSK101-1 General Characteristics Department Made up of widely separated cells. Supported by abundant intercellular substance. Contains C.T. fibers. Penetrated by blood vessels, lymphatics and nerves.  Histology MSK101-1 Embryonic Origin Department Mesodermal  Histology MSK101-1 General Functions Department Connects and binds cells and organs. Gives mechanical support to tissues and organs. Divides the organs into compartments. Stores fat and certain minerals. Protects against infection. Helps wound healing and tissue repair. Medium for exchange of metabolites between blood and tissues.  Histology MSK101-1 Components Department CELLS MATRIX Fibers Connective Tissue  Histology MSK101-1 Types of C.T. according to Department matrix consistency Soft C.T. proper Rubbery Cartilage Hard Bone Fluid Blood  Histology MSK101-1 Department UMCs & Pericytes Reticular Fibroblasts Cells FIXED & Fibrocytes C.T. Cells Stable/ Long lived Macrophages Adipocytes  Histology MSK101-1 Department Plasma Cell FREE Transient Mast C.T. Cells Leukocytes Cell /Short lived Macrophage  Histology MSK101-1 Undifferentiated Mesenchymal Department Cell Unspecialized primitive cells. In adults: permanent source of cells (B.M.). LM small, branched cell. pale blue cytoplasm. Central oval pale nucleus with clear nucleoli. EM Many free ribosomes and few other organelles.  Histology MSK101-1 Department  Histology MSK101-1 Department Functions Divides actively and Differentiates into: 1. Other types of C.T. cells. 2. Smooth muscle cells. 3. Endothelial cells.  Histology Pericyte MSK101-1 Department Origin: UMC. Site: Around blood capillaries.  Histology MSK101-1 Department LM: (as UMC) small, branched cell. pale blue cytoplasm. Central oval pale nucleus with clear nucleoli. EM: many free ribosomes/ few other organelles+ actin and myosine filaments.  Histology MSK101-1 Department Functions 1. Adult mesenchymal stem cell=??? 2. In case of injury it can differentiate into: Smooth muscle cells. Endothelial cells. Other types of C.T. cells. 3. Vasoconstriction of capillaries.  Histology MSK101-1 Fibroblasts & Fibrocytes Department Origin: UMC & pericytes. Site: most common, present in all types of C.T. proper. MSK101-1 LM Histology Department Fibroblast Fibrocyte (Young, Immature) (Old, Mature) Many branches Spindle-shaped with few processes Deep basophilic Pale basophilic cytoplasm cytoplasm Large pale oval Small dark rounded nucleus nucleus MSK101-1 EM Histology Department Fibroblast Fibrocyte (Young, Immature) (Old, Mature) Well-developed rER Few organelles Well-developed Golgi complex Many mitochondria Euchromatic nucleus Heterochromatic nucleus  Histology MSK101-1 Functions Department Fibroblast Fibrocyte (Young, Immature) (Old, Mature) Synthesis of C.T. fibers. Continuous slow turnover of fibers and matrix Synthesis of ground (maintenance). substance. Secretion of growth factors. Activated to fibroblast during healing Healing of C.T.  Histology MSK101-1 Adipocytes (Fat Cells) Department Origin: UMC. Site: Adipose C.T. 1. White subcutaneous, perinephric. 1. Brown interscapular, mediastinal.  Histology MSK101-1 LM Department Unilocular Adipocyte Multilocular Adipocyte Large and oval. Smaller and rounded Single giant fat droplet. Multiple small droplets. (Signet ring appearance) Peripheral flat nucleus Eccentric rounded nucleus Stains orange with Sudan III. Stains orange with Sudan III.  Histology MSK101-1 EM Department Unilocular Adipocyte Multilocular Adipocyte Abundant sER. Less developed sER. Few filamentous mitochondria. Many rounded mitochondria. Single large electron dense fat Multiple electron dense fat droplet. droplets.  Histology MSK101-1 Functions Department Unilocular Adipocyte Multilocular Adipocyte Synthesis and storage of fat. Organ support. Thermogenesis by action Heat insulation. of thermogenin on fat. Endocrine function : leptin increases metabolic rate and decrease food intake.  Reticular Cell Histology MSK101-1 Department Origin: UMC. Site: Stroma of glands and organs. LM: Stellate cells. Basophilic cytoplasm. Central pale nucleus.  Histology MSK101-1 Department EM Variable amount of organelles. Cell junctions between processes. Functions Secrete reticulin. Mechanical support. Phagocytic activity. Antigen presenting cell.  Histology MSK101-1 Macrophage Department Origin: blood monocyte. Site: fixed&free. LM Large irregular cell. Basophilic granular cytoplasm. Eccentric dark kidney- shaped nucleus. Vital stains (Indian ink).  Histology MSK101-1 Department EM Irregular shape. Rich in lysosomes. Prominent Golgi. Functions: 1. Phagocytic activity. 2. Form multinucleated foreign body giant cells. 3. Antigen presenting cell (APC). 4. Destruction of old RBCs in liver & spleen.  Histology MSK101-1 Pigment Cells Department Origin: UMCs. Have long branching processes. LM Small stellate cells. Cytoplasm is pale basophilic with scattered dark brown melanin granules. Function: They carry melanin pigment granules in skin dermis and iris of the eye.  Histology MSK101-1 Department