Tecido Conjuntivo

	Veterinary Histology UFF Department of Morphology - Biomedic Institute LaBEc - Laboratory of Cellular and Extracellular Biomorphology
	Veterinary Histology Atlas
			Versão em Português

Introduction

Connective Tissue Proper
General Characteristics • Heterogeneous Cell Population • Highly vascularised and innervated • Establishes a continuation with other tissues, being responsible for the functional integration of the organism Functions • Support (Physical Support) • Filling in • Exchange medium (metabolic wastes, nutrients and oxygen) • Defense and Protection (defense cells have quick access to many regions in the body)
Classification Dense Connective Tissue: Few Cells, there are mostly fibers and extracellular matrix
	Regular: Fibers organized towards the same direction
	Irregular: Fibers don’t have a specific organization
Loose Connective Tissue: Present Fibers and Extracellular Matrix with a predominance of cells

Components I - Cells Fibroblast: • Young cell responsible for synthesizing the Extracellular matrix • Multiply during the healing of wounds • Possess cytoplasmic projections • Spindle-shaped • Elongated Nucleus with a Pale Chromatin(high activity rate) • Characteristics of a Secreting Cell (well developed R.E.R. and G.A.)
Fibrocyte: • Adult Stage of the Fibroblast, responsible for the maintenance of the Extracellular Matrix • Can return to its younger stage and synthesize in great amounts in case of extreme Cellular Repair • Elongated Nucleus with a Denser Chromatin (small synthesis of protein)
Macrophages: • Origin: Monocyte (leucocyte) • Part of the Mononuclear Phagocyte System • Function: Phagocyte antigens • Shape: Pleomorphic, because it emits pseudopodia • Reniform Nucleus and Basophilic Coloring sófila
	Mast cell: • Globulous Cell shape, Round and Central Nucleus • Chemical signaler that accelerates the local immune response • Involved in Inflammatory and Allergic Processes • Possess Receptors for IgE • Cytoplasm filled with basophilic granules: - Heparin: biological anticoagulant - Histamine: Vasodilator and increases the cell permeability • Secretes ECF- A (Eosinophil chemotactic factor of anaphylaxis) • Secretes SRS- A ( slow reacting substance)
	Lymphocyte: • Small and Globulous Cell • Nucleus with Dense Chromatin • Great Nucleus/Cytoplasm relation
Lymphocyte B • Differentiation in the Bursa of Fabricius(birds) • Mammals, in specific areas of the red bone marrow • Differentiate themselves into Plasmocytes Lymphocyte T • Suffer cellular differentiation in the thymus • Responsible for the cellular immune response(CD4 and CD8)
Plasmocyte: • Antibody-secreting cell • Characteristics of a secreting cell (well developed R.E.R. and G.A.) • Round and eccentric nucleus(dense and pale chromatin, radiated)
Adipocytes
	Functions: • Storage of lipids • Absorption of impacts • Heat insulator • Store liposoluble vitamins • Necessary for the synthesis of steroid hormones • All Cell Membranes need lipids • Can be use for the production of energy • Form the Panniculus, layer beneath the hypoderm • In optical microscopy, the negative image of the lipid is observed for it’s been dissolved by the alcohol.
	Unilocular Adipocyte: • White fat • Present a single fat droplet • Flat and peripheral nucleus • Well developed S.E.R. • Supplies lipids to the multilocular adipocyte
Multilocular Adipocyte: • Brown fat • In mammals it’s present only in newborns(heat regulation) • Cytoplasm with a lot of fat droplets • Round nucleus • High concentration of mitochondria • All of the ATP produced in the cell is dissipated in the form of heat
Undifferentiated Mesenchymal Cells: • Differentiate into Connective Tissue cells (fibroblast and adipocyte) • Possess a shape very similar to a fibrocyte
II - Extracellular Matrix Components: • Fibers: Collagen and elastic • Ground Substance Collagen Fibers: • Protein filaments formed by collagen • 3 polypeptide chains in alfa-helix • The more fibrous, the more resistant • Present in the Dermis, Bones, Tendons, Ligaments, and others - Fibril: formed by filaments - Fiber: aggregated fibrils Types: I • High Packing Rate, forming fibers • Present in the Dermis, Tendons, Bones and Ligaments II • Low Packing Rate – Fibril • Present in Cartilage III • Thin fibers (Reticular) • Function is to Support Organs • Not visualized by H.E. • Specific staining: argentic impregnation • Present in Hepatic, Splenic stroma and more IV • Low Packing Rate – Thin Fibrils • Present in Basal Lamina Ultra-structure: • Present Transverse Periodicity, with a gap of approximately 67nm • Stains: Heavy metals, osmium tetroxide ,lead, uranyl
Elastic Fibers: • Protein Filament formed by the elastin protein Elastogenesis: • Formation of Elastin • Fibroblasts synthesize the Fibers and Microfilaments (Fibrillins) • The more Elastin there exists, the less Fibrillin there will be (inversely proportional) Oxytalanic • First phase of formation • Microfilaments make a mold to receive the elastin Elauninic • Intermediate phase • Microfilaments and Elastin Elastic Fiber Proper • Most developed phase • There are no more Microfilaments Types: Elastic • Yellowish in fresco • O.M.: Normally thicker, stained with orcein • E.M.: Just Elastin Elauninic • O.M.: Intermediate Fiber • E.M.: Few Elastin and Presence of Microfilaments (fibrillins) Oxytalanic • O.M.: Thin Fiber • E.M.: Only Microfilaments(Fibrillins) Specific Staining: • Orcein • Resorcinol-fucsina(Weigert’s)
III - Ground Substance Function: • Maintain the Continuous Hydration of the Tissue Formed of: Glycosaminoglycans (GAGs) • Long-chain Polysaccharides chemically linked to water • Examples: Dermatan Sulfate, Keratan sulfate, chondroitin-4-sulfate, Hyaluronic Acid Proteoglycans • Link proteins • Link many Lateral GAG Chains Non-collagenous glycoproteins • Examples: Fibronectin and Laminin, forms the Basal Lamina