Connective Tissue Histology Notes PDF

MODULE 3: CONNECTIVE TISSUE Mary Judith S. Rebosa, MD, FPPS Faculty, Biology Department Our Lady of Fatima University  UNIT EXPECTED OUTCOMES Describe the general histological characteristics and functions of the different kinds of connective tissues Classify the connective t...

MODULE 3: CONNECTIVE TISSUE Mary Judith S. Rebosa, MD, FPPS Faculty, Biology Department Our Lady of Fatima University  UNIT EXPECTED OUTCOMES Describe the general histological characteristics and functions of the different kinds of connective tissues Classify the connective tissues based on the characteristics of its cellular and extracellular components Analyze selected photomicrographs of connective tissues Correlate connective tissue changes with some common diseases/disorders  PART I: CONNECTIVE TISSUE PROPER CONNECTIVE TISSUE Mesodermal in origin Fewer cells that epithelial tissue due to abundant ground substance https://www.verywellhealth.com/what-is-connective-tissue-190043 CONNECTIVE TISSUE Supports and binds together other structural elements throughout the body Structural framework of many organs CONNECTIVE TISSUE STRUCTURAL PROPERTIES Tensile strength: resist pulling, stretching, and tearing Elasticity: facilitate return to original shape after mechanical distortion Volume: provided by glycoproteins and complex carbohydrates which form the ground substance CONNECTIVE TISSUE FUNCTIONS Support and packing: Capsules around organs, tendons, ligaments, areolar tissues that fill up spaces between organs Bone and Cartilage Storage: Lipids stored in the adipose tissue Loose connective tissue stores water and electrolytes Transport: Medium through which nutrients and metabolic wastes are exchanged between cells and their nourishing blood supply CONNECTIVE TISSUE FUNCTIONS Defense: Phagocytes and Plasma Cells (antibody-producing cells) Repair: Capacity for regeneration  MAJOR GROUPS Connective tissue proper Special types of connective tissue Cartilage Bone Blood Hemopoietic Tissue Myeloid Lymphoid Tissue https://legacy.owensboro.kctcs.edu/gcaplan/anat/notes/API%20Notes%20F%20Connective%20Tissues.htm  COMPOSITION CONNECTIVE TISSUE CELLS Fixed or permanent Responsible for production and maintenance of extracellular components and storage of fuels Wandering/Mobile EXTRACELLULAR MATRIX Proteoglycans CONNECTIVE TISSUE FIBERS Collagen Reticular Elastic https://www.intechopen.com/books/tissue-regeneration/the-role-of-extracellular- matrix-in-tissue-regeneration CONNECTIVE TISSUE PROPER Found all over the body Composed of cells and extracellular substance of matrix Functions Envelops muscles Binds body parts together Forms the stroma or supporting framework of various organs Venue for the exchange of gases and substances Provides cells needed for immunity CONNECTIVE TISSUE PROPER: MATRIX Ground Substance Fibers https://www.zoology.ubc.ca/~biomania/tutorial/tuthisto/ct01. htm CONNECTIVE TISSUE PROPER: MATRIX Ground Substance Amorphous, homogenous, transparent, hydrated gel Consists mainly of water PROTEOGLYCANS Main structural constituents Stabilizes water Responsible for gelatinous character Consists of a core protein to which glycosaminoglycans are attached covalently in a radiating pattern https://www.zoology.ubc.ca/~biomania/tutorial/tuthisto/ct01.htm CONNECTIVE TISSUE PROPER: MATRIX Ground Substance GLYCOSAMINIOGLYCANS (GAGs) Render ground substance acidic Hyaluronic acid Most abundant Backbone to which proteoglycan molecules are attached by link proteins to form proteoglycan aggregates Keratin Sulfate, Chondroitin Sulfate, Dermatan Sulfate, Heparin Sulfate STRUCTURAL GLYCOPROTEINS Fibrillar, Fibrillin, Fibronectin https://themedicalbiochemistrypage.org/glycans.php CONNECTIVE TISSUE PROPER: MATRIX Ground Substance STRUCTURAL GLYCOPROTEINS Fibrillar For formation of elastic fibers Fibronectin Laminin Thrombospondin CONNECTIVE TISSUE PROPER: MATRIX Extracellular Fibers Supportive function of connective tissue COLLAGEN FIBERS Main fibers present in all connective tissues Acidophilic: pink in H&E preparations Blue with Masson’s Trichrome technique https://themedicalbiochemistrypage.org/glycans.php CONNECTIVE TISSUE PROPER: MATRIX Extracellular Fibers COLLAGEN FIBERS Slightly flexible Inelastic Most abundant protein CONNECTIVE TISSUE PROPER: MATRIX Extracellular Fibers RETICULAR FIBERS Type III collagen Branching network Argyrophilic Fibers Stain black with silver salts React positively to PAS reagent https://www.leicabiosystems.com/knowledge-pathway/special-stains-which-one-how-and-why- part-ii-connective-tissue CONNECTIVE TISSUE PROPER: MATRIX Extracellular Fibers RETICULAR FIBERS Found in bone marrow, liver, lymphoid organs (lymph nodes and spleen) Comprise the fibrillar component of the lamina fibroreticularis of the basement membrane CONNECTIVE TISSUE PROPER: MATRIX Extracellular Fibers ELASTIC FIBERS Fine fibers that have anastomosing branches Impart yellow color to fresh tissue Blue or black with Orcein Selectively stained by Resorcin-Fuschin and Aldehydefuschin dyes CONNECTIVE TISSUE PROPER: MATRIX Extracellular Fibers ELASTIC FIBERS Consists of a homogenous amorphous core made up of elastin surrounded by longitudinal bundles of microfibrils that consist mostly of fibrillin very supple but less tensile strength CONNECTIVE TISSUE PROPER: MATRIX Extracellular Fibers ELASTIC FIBERS Elastin Responsible for elasticity Found mostly in ligament flava between vertebrae, extracellular spaces of the auricles and external acoustic meatus of the ear, external nose, auditory tube, epiglottis, and some parts of the larynx  CELLS IN CONNECTIVE TISSUE RESIDENT CELLS (Fixed or Permanent) Responsible for production and maintenance of extracellular components and for storage of reserve fuel Fibroblasts and Fibrocytes Reticular Cells Adipose Cells Mast Cells Resident Macrophages  CELLS IN CONNECTIVE TISSUE VISITING CELLS (Free, Mobile, or Wandering Cells) Concerned with short-term tissue reaction in injury Inflammatory macrophages Plasma cells Leukocytes (neutrophils, monocytes, lymphocytes) CELLS IN CONNECTIVE TISSUE  CELLS IN CONNECTIVE TISSUE MESENCHYMAL CELLS Originate from pluripotent cells Irregularly stellate-shaped cells with branching processes Have oval nuclei http://www.omicsonline.org/2157-7633/images/2157-7633-1-105-g001.gif  CELLS IN CONNECTIVE TISSUE ORIGINS OF CONNECTIVE TISSUE CELLS Nearly all connective tissue cells have common stem Some variant of the fibroblast is always present https://www.researchgate.net/figure/From-mesenchymal-stem-cells-to-specific- connective-tissue-cell-types-Undifferentiated_fig1_315526863  CELLS IN CONNECTIVE TISSUE FIBROBLASTS Most abundant Principal cell type of Connective Tissues Produce proteins, glycoproteins, and GAG Produce the precursors of collagen, elastic, and reticular fibers  CELLS IN CONNECTIVE TISSUE FIBROBLASTS Proliferate in response to tissue damage Fusiform or spindle-shaped With oval or elongated nucleus One or two distinct nucleoli Small finely granular chromatin https://encrypted- tbn1.gstatic.com/images?q=tbn:ANd9GcTFnLHsaicYf0o6MU- 0t0Apce9rZSTdj059pzvzVQt1dnSgjI0k  CELLS IN CONNECTIVE TISSUE FIBROCYTES Old and inactive fibroblasts Sparse cytoplasm Weakly basophilic Scanty ER Capacity for growth and regeneration Fixed cells of connective tissue http://intranet.tdmu.edu.ua/data/kafedra/internal/histolog/classes_stud/en/stomat/ptn/1/07%20Connective%20tissues.%20Loose%20connective%20tissue.%20 Dense%20connective%20tissue.%20Connective%20tissues%20with%20special%20properties..files/image031.jpg  CELLS IN CONNECTIVE TISSUE ADIPOSE CELLS/FAT CELLS/ADIPOCYTES Store neutral fats (triglyceride) in its cytoplasm Distribution Areolar tissue Small blood vessels Adipose tissue Incapable of mitotic division New fat cells arise from mesenchymal cells https://encrypted- tbn2.gstatic.com/images?q=tbn:ANd9GcQ7ilbev9VCPT78SJu69U-NKC1ac7- NkMZpgR2PJG9U5xnMXxso4w  CELLS IN CONNECTIVE TISSUE ADIPOSE CELLS/FAT CELLS/ADIPOCYTES Appear as glistening droplets of oil surrounded by a thin rim of cytoplasm Each cell contains a single large droplet of oil In H&E, they consist of a large empty space with a flattened nucleus on one side of the cell Signet Ring Cells https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcQ7ilbev9VCPT78SJu69U- NKC1ac7-NkMZpgR2PJG9U5xnMXxso4w  CELLS IN CONNECTIVE TISSUE RETICULAR CELLS Specialized fibroblasts that synthesize precursors of Type 3 Collagen Distribution Hemopoietic Tissue Lymphoid Organs Liver Larger than fibroblasts and with large and lightly-stained nucleus Long cytoplasmic processes that embrace reticular fibers https://encrypted- tbn2.gstatic.com/images?q=tbn:ANd9GcQ7ilbev9VCPT78SJu69U- NKC1ac7-NkMZpgR2PJG9U5xnMXxso4w  CELLS IN CONNECTIVE TISSUE MACROPHAGES (PHAGOCYTES/HISTIOCYTES) Phagocytes which differentiate from monocytes Classification Fixed or Resting Macrophages Attached to Collagen Fibers Free or Wandering Macrophages Wander about in the extracellular matrix https://en.wikivet.net/Macrophages  CELLS IN CONNECTIVE TISSUE MACROPHAGES (PHAGOCYTES/HISTIOCYTES) Resident Macrophages Inhabit a given site Not immunologically active Maintain their numbers in a particular tissue Undergo local proliferation http://histology.med.yale.edu/respiratory_system/respiratory_system_reading. php  CELLS IN CONNECTIVE TISSUE MACROPHAGES (PHAGOCYTES/HISTIOCYTES) Inflammatory Macrophages Migrate to a site in response to a stimulus after differentiating from monocytes Do not proliferate locally Increase their number by differentiating from monocytes http://www.nature.com/ni/journal/v6/n9/images/ni0905-861-F1.jpg  CELLS IN CONNECTIVE TISSUE MACROPHAGES (PHAGOCYTES/HISTIOCYTES) Irregularly-shaped cells with short blunt processes Occasional long, slender branching processes Capable of amoeboid movement Cytoplasm may contain small vacuoles http://www.nature.com/ni/journal/v6/n9/images/ni0905-861- F1.jpg  CELLS IN CONNECTIVE TISSUE MACROPHAGES (PHAGOCYTES/HISTIOCYTES) Distribution Loose connective tissues Richly vascularized areas Agents of defense Act as scavengers because of their phagocytic activity (inflammatory response) Serve as antigen-presenting cells (immune response) https://encrypted- tbn1.gstatic.com/images?q=tbn:ANd9GcRKOFBuxYyXwo3wFmpq68 tuqan05iVT3WrBpQag2wtC5JmtFU85  CELLS IN CONNECTIVE TISSUE MAST CELLS Distribution Lamina propria of GIT and respiratory tract Underneath the skin Along small blood vessels Large ovoid cells with centrally located spherical nuclei with granules Numerous cytoplasmic granules Granules contain heparin (anti- coagulant) and histamine (vasodilator) Possess microvilli Basophilic http://www.mastopedia.com/tiki-download_file.php?fileId=5&display  CELLS IN CONNECTIVE TISSUE MAST CELLS Functions Immediate-type Hypersensitivity Reactions (Anaphylaxis) Release leukotrienes, prostaglandins, and cytokines during inflammation Wound healing Defense against pathogens https://encrypted- tbn0.gstatic.com/images?q=tbn:ANd9GcQz0fL783ixpcOYADtzNQzUqcrRcQXsSmXMCQZtdisx EhAPrSNWqA  CELLS IN CONNECTIVE TISSUE BASOPHILS Similar to mast cells but smaller, more mobile, and have a shorter life span With cytoplasmic granules Contain histamine and heparin Role in inflammation and immediate- type hypersensitivity reactions http://www.mastopedia.com/tiki-download_file.php?fileId=5&display  CELLS IN CONNECTIVE TISSUE PLASMA CELLS Distribution Serous membranes Lymphoid tissue Chronic inflammation Lamina propria of digestive tract Major producers of antibodies http://www.mastopedia.com/tiki-download_file.php?fileId=5&display  CELLS IN CONNECTIVE TISSUE PLASMA CELLS Ovoid, irregularly-shaped cells Small, eccentrically-placed nucleus Basophilic cytoplasm Chromatin present in clumps near the nuclear membrane Clock-face or Cartwheel Appearance Well-developed rough ER http://www.mastopedia.com/tiki-download_file.php?fileId=5&display CONNECTIVE TISSUE PROPER https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcTXX1jUBUrKAinHSvNqEeH71eoGKHLnyM5GH2BjSzRO- ENHiI2JbQ  CONNECTIVE TISSUE PROPER LOOSE CONNECTIVE TISSUE Distribution Hypodermis Tunica adventitia of blood vessels Lamina propria Submucosa of digestive, respiratory, and urogenital tracts https://encrypted- tbn3.gstatic.com/images?q=tbn:ANd9GcTXX1jUBUrKAinHSvNqEeH71eoGKHLnyM5 GH2BjSzRO-ENHiI2JbQ  CONNECTIVE TISSUE PROPER LOOSE CONNECTIVE TISSUE Most abundant connective tissue Highly vascularized Abundant extracellular substance Irregular arrangement of fibers Distribution Hypodermis Tunica Adventitia of Blood Vessels Lamina Propria and Submucosa of the Digestive, Respiratory, and Urogenital Tracts http://faculty.ksu.edu.sa/75719/Pictures%20Library/Types%20of%20tissues/Lo ose%20Connective%20tissue.jpg  CONNECTIVE TISSUE PROPER LOOSE CONNECTIVE TISSUE Ordinary Loose CT Predominant extracellular fiber: COLLAGEN Predominant resident cell: FIBROBLAST Modified Loose CT Adipose Tissue Reticular Tissue Elastic Tissue Mucous Tissue  CONNECTIVE TISSUE PROPER LOOSE CONNECTIVE TISSUE http://legacy.owensboro.kctcs.edu/gcaplan/anat/Histology/API%20histo%20connective.htm https://bcrc.bio.umass.edu/courses/spring2018/biol/biol523/content/loose-areolar-connective-tissue-40x  CONNECTIVE TISSUE PROPER ADIPOSE TISSUE Largest energy storage site of the body Thermal insulator Maintains a stable supply of fuel by accumulating lipids in periods of excess food intake and releasing fatty acids in periods of fasting Shock absorber (soles of feet and around the kidneys) http://faculty.ksu.edu.sa/75719/Pictures%20Library/Types%20of%20tissues/Loo se%20Connective%20tissue.jpg  CONNECTIVE TISSUE PROPER ADIPOSE TISSUE Distribution Subcutaneous tissue Fat depots Types Yellow/White Adipose Stores lipids in a single fat vacuole Brown Adipose Tissue Hibernating species and newborns (non-shivering thermoregulation) Store lipids in the form of numerous droplets https://www.ahajournals.org/doi/full/10.1161/circulationaha.111.042929  CONNECTIVE TISSUE PROPER ADIPOSE TISSUE Fat Cells Grouped into fat lobules separated by fibrous septa Each cell is surrounded by reticular fibers Fibers Collagenous and elastic fibers Ground Substance Scanty Blood Vessels Abundant https://aandpeasyaspanda.wordpress.com/2011/10/20/connective-tissue/  CONNECTIVE TISSUE PROPER RETICULAR TISSUE Distribution Hemopoietic Tissue Myeloid and Lymphoid Tissue Liver Lymphoid Organs https://aandpeasyaspanda.wordpress.com/2011/10/20/connective-tissue/  CONNECTIVE TISSUE PROPER ELASTIC TISSUE Form bundles arranged parallel to each other With few collagenous fibers and fibroblasts Distribution Ligamentum flava of vertebral column Suspensory ligament of the penis https://legacy.owensboro.kctcs.edu/gcaplan/anat/notes/API%20Notes%20F%20Connective%20T issues.htm  CONNECTIVE TISSUE PROPER MUCOUS TISSUE Common in embryo: Wharton’s Jelly Abundant amorphous and jelly-like ground substance Few collagen, elastic, and reticular fibers Ground substance composed mainly of hyaluronic acid Few fibroblasts and macrophages https://www.anatomyatlases.org/MicroscopicAnatomy/Section03/Plate0351.shtml  CONNECTIVE TISSUE PROPER DENSE CONNECTIVE TISSUE Contains an abundance of closely packed collagen fibers in its extracellular matrix Few cells and scanty intercellular ground substance http://faculty.ksu.edu.sa/75719/Pictures%20Library/Types%20of%20tissues/Loose%20Connective%20tissue.jpg  CONNECTIVE TISSUE PROPER DENSE REGULAR CONNECTIVE TISSUE Fibers arranged in a definite pattern http://faculty.ksu.edu.sa/75719/Pictures%20Library/Types%20of%20tissues/Loose%20Connectiv e%20tissue.jpg  CONNECTIVE TISSUE PROPER DENSE REGULAR CONNECTIVE TISSUE Distribution Tendons Ligaments Ligaments of Vertebrae http://medcell.med.yale.edu/histology/connective_tissue_lab/dense_regular_connective_tissue.ph p  CONNECTIVE TISSUE PROPER DENSE IRREGULAR CONNECTIVE TISSUE Collagen fibers run in various directions Distribution Dermis Capsule of liver Sheaths of large nerves and arteries Dura Mater Tunica Albuginea of Testes  CONNECTIVE TISSUE PROPER ELASTIC DENSE CONNECTIVE TISSUE Contains numerous elastic fibers in addition to collagen fibers http://bodterms.weebly.com/elastic-connective-tissue.html  PART II: SPECIALIZED CONNECTIVE TISSUE CARTILAGE AND BONES Special types of connective tissues Dense Regular Connective Tissues With few cells and abundant intercellular substance Cartilage: gelatinous intercellular substance Bone: calcified intercellular substance  CARTILAGE 3 Elements CELLS Chondrocytes Inside cavities called lacunae FIBERS Collagen Elastic INTERCELLULAR MATRIX (GROUND SUBSTANCE)  CARTILAGE Differences from Regular Connective Tissue Rigid matrix No blood and lymphatic vessels No nerves http://m.np.is/peterarnold/s/np04717012.jpg  CARTILAGE CHONDROCYTE Cytoplasm Finely granular and basophilic Limited number of mitochondria Well-developed Rough ER and Golgi Complex With inclusions (fat droplets and glycogen) With cytoplasmic processes http://www.cdaarthritis.com/images_slides/10_carilage_b_chondrocyt e_1024.jpg  CARTILAGE CHONDROCYTE Nucleus Ovoid Chromatin granules are either on the inner aspect of the nuclear membrane or form clumps within the nucleus  CARTILAGE CHONDROCYTE Mature Not capable of mitosis Young Undergo mitosis Isogenous Cells Daughter cells http://faculty.une.edu/com/abell/histo/hycart2.gif  CARTILAGE MATRIX Consists of Ground Substance Extracellular Fibers Ground Substance Water: 70-80% wet weight Proteoglycan Glycosaminoglycans Non-collagenic Proteins Glycoproteins http://faculty.une.edu/com/abell/histo/hycart2.gif  CARTILAGE MATRIX Ground Substance Territorial Matrix (Capsule) Intercellular substance immediately surrounding a lacuna Rich in GAGs More basophilic Pericellular Capsule Innermost layer Protects chondrocytes against mechanical stress http://www.dartmouth.edu/~anatomy/Histo/lab_2/bone/D MS065/07.gif  CARTILAGE MATRIX Ground Substance Interterritorial Matrix Area in between territorial matrices Chondronectin Promotes adherence of collagen fibers to the cell surface of the chondrocytes  CARTILAGE TYPES According to the kind and amount of fibers Hyaline Adult Articular Fetal Elastic Fibrocartilage  HYALINE CARTILAGE Most abundant cartilage Glistening smooth pearly white Consists of type II collagen fibers Fetal Cartilage: temporary skeleton for the fetus Distribution Epiphyseal Plates at the end of long bones Adult Cartilage Distribution Articular cartilage, Trachea, Bronchi, Larynx, Nose, Ears, Costal cartilage  HYALINE CARTILAGE http://histology-world.com/photoalbum/albums/userpics/hyalinelabel.jpg http://www.montgomerycollege.edu/~wolexik/Hyaline%20Cartilage-200x-All%20Labels-08163149%20copy.jpg  ELASTIC CARTILAGE Less abundant matrix Fibers Collagen Type II Fibrils Elastic Fibers: account for its pliability and yellowish color Distribution Auricle External Acoustic Meatus Epiglottis Parts of the Larynx http://farm3.staticflickr.com/2509/5814146817_fd829cf55b_z.jpg  FIBROCARTILAGE Withstands greater stress Type I Collagen Fibers – thicker Transitional stage between dense regular connective tissue and cartilage No distinct perichondrium Distribution Intervertebral discs Articular discs Glenoid and acetabular labra Tendons Ligaments http://legacy.owensboro.kctcs.edu/gcaplan/anat/Notes/Fibrocartilage_H&E _PA112036_lbd.jpg FIBROCARTILAGE http://www.stegen.k12.mo.us/tchrpges/sghs/ksulkowski/imag es/39_Fibrocartilage_Connective_Tissue.jpg  PERICHONDRIUM Made up of dense irregular connective tissue which envelops almost all cartilages except articular cartilages Has chondrogenic potency: ability to form cartilage Responsible for subsequent growth and repair of cartilage http://jacusers.johnabbott.qc.ca/~paul.anderson/JOINTLAB/perichondrium.JPG  GROWTH OF CARTILAGE Interstitial Growth Endogenous Growth Appositional Growth Exogenous Growth DEGENERATIVE CHANGES OF CARTILAGE With aging, cartilage becomes less cellular and translucency decreases Decrease in glycosaminoglycan content Calcification Most important retrogressive change Cartilage becomes hard and brittle-like bone due to deposition of calcium phosphate and calcium bicarbonate http://ts1.mm.bing.net/th?id=H.4842538188541904&pid=1.7 DEGENERATIVE CHANGES OF CARTILAGE  BONE http://www.mhhe.com/biosci/esp/2001_saladin/folder_struct ure/su/m2/s1/assets/images/sum2s1_1.jpg  BONE TISSUE Bone Matrix Arranged in thin layers called Lamellae Lacunae: cavities occupied by osteocytes Canaliculi Endosteum Lines the medullary, marrow, and vascular cavities Periosteum Fibrous Layer: outer layer Osteogenic Layer: inner layer containing osteoprogenitor cells http://upload.wikimedia.org/wikipedia/commons/3/34/Illu_compact_spongy_bone.jpg  BONE TISSUE SPONGY BONES Consists of Trabeculae or spicules Red bone marrow http://www.sciencephoto.com/image/301862/large/P1160041- Macrophoto_of_human_spongy_bone-SPL.jpg  BONE TISSUE SPONGY BONES http://classroom.sdmesa.edu/anatomy/Histologyphotos/Conn ective/spongybone40xlabeled.jpg  BONE TISSUE SPONGY BONES http://www.glenoaks.edu/facultystaff/FacultyWebSites/hartung/PublishingImages/Bones/Bone%20histology/14%20bone%20spongy%20bone%20- %20bone%20450X%20labeled.jpg  BONE TISSUE COMPACT BONES Organization of Lamellae Haversian System Interstitial Lamellae Circumferential Lamellae http://histology- world.com/photoalbum/albums/userpics/bone3label.jpg  BONE TISSUE COMPACT BONES Volkmann’s Canal Connects Haversian Canals to each other https://www.britannica.com/science/Volkmann-canal  BONE TISSUE COMPACT BONES Interstitial Lamellae Bone lamellae not arranged around a haversian canal http://histologyatlas.wisc.edu/slides/257/labeled  BONE TISSUE COMPACT BONES Circumferential Lamellae Outer Circumferential Lamellae Immediately beneath the periosteum Several layers which encircle the whole bone in the diaphysis Inner Circumferential Lamellae Encircle the whole medullary cavity http://www.lab.anhb.uwa.edu.au/mb140/CorePages/Bone/images/bon11sc.jpg  BONE MATRIX GROUND SUBSTANCE Water Organic Substances Inorganic Minerals Proteoglycan molecules Calcium Few glycosaminoglycans Phosphorus (calcium Non-collagenic Proteins hydroxyapatite crystals) Glycoproteins Bicarbonate, citrate, Extracellular Fibers magnesium, potassium, Type I collagen fibers sodium 90% of organic content  BONE CELLS Osteoprogenitor cells Osteoblasts Osteocytes Osteoclasts https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Book%3A_General_Biology_(Boundles s)/38%3A_The_Musculoskeletal_System/38.2%3A_Bone/38.2B%3A_Cell_Types_in_Bones  BONE CELLS OSTEOPROGENITOR CELLS Differentiate from mesenchymal cells Differentiate into osteoblasts or chondroblasts Form the layer of cells of periosteum and endosteum Fusiform-shaped https://www.memorangapp.com/flashcards/76009/Week+14+- +Bone+%28Histology%29/  BONE CELLS OSTEOBLASTS Differentiate from osteoprogenitor cells Synthesize precursors of collagen fibers and organic constituents of bone matrix Secrete growth factors that promote bone growth Aid osteoclasts in bone resorption Transform into osteocytes https://www.memorangapp.com/flashcards/76009/Week+14+- +Bone+%28Histology%29  BONE CELLS OSTEOCYTE Occupy the lacunae in bone tissue Flat cells with numerous cytoplasmic processes Osteoid Tissue Layer of tissue which separates the osteocyte within a lacuna from the calcified matrix https://www.ouhsc.edu/histology/Text%20Sections/Bone.html  BONE CELLS OSTEOCLAST Large multinucleated cells on the surfaces of bone Agent of bone resorption Found in Howship’s Lacunae https://www.ouhsc.edu/histology/Text%20Sections/Bone.html  BONE CELLS OSTEOCLAST Striated Border (Ruffled Border) Formed by the surface of the osteoclast that abuts on the bone Consists of villus-like processes of plasmalemma Increases the active surface of the osteoclast Traps small particles to be subjected to enzymatic activity Originate from the Colony- Forming Unit-Granulocyte Macrophage  CLOSURE OF EPIPHYSEAL PLATE The end of increase in length of the bone Event when the cartilage cells stop dividing and the cartilage plate is replaced completely by bone http://www.naturalheightgrowth.com/wp- content/uploads/2012/08/GrowthPlates.jpg  NUTRITIONAL EFFECTS ON BONE DEFICIENCY IN THE FOLLOWING: Calcium: poor mineralization Phosphorus: poor mineralization Vitamin D: rickets, osteomalacia Vitamin C: scurvy Vitamin A: affects osteoblasts and osteoclasts Retards bone growth. REFERENCES Gonzales, E. ( 2014 ) Esteban and Gonzales’ Textbook of Histology 5th ed. ( ch 3 )C & E publishing inc. Mescher, A. L. (2018). Junqueira's basic histology: text and atlas 15th ed. New York:McGraw Hill/Medical. VanPutte, C. (2016). Seeley’s essentials of anatomy and physiology ( 11th ed.). New York:McGraw- Hill Higher Education Young, B. (2014). Wheater's functional histology: a text and colour atlas 6th ed.(pp.65-81). Edinburg: Churchill Livingstone. THANK YOU!