Connective Tissue PDF

Connective tissue --------------------------------------------------------------------------------------------------------- CONNECTIVE TISSUE Connective tissue is the most diverse of the four tissue types with a wide variety of functions. It ranges in consistency fr...

Connective tissue --------------------------------------------------------------------------------------------------------- CONNECTIVE TISSUE Connective tissue is the most diverse of the four tissue types with a wide variety of functions. It ranges in consistency from the gel-like softness of areolar connective tissue to the hardness of bone. Blood is also a connective tissue. Connective tissue (C.T) forms an extensive compartment in the body and can be considered as the "glue" that holds the body together. * Mesodermal in origin and consisted of:- 1) CT ground substance. 2) CT fibers. 3) CT cells. Chapter 3 --------------------------------------------------------------------------------------------------------- Types of Connective tissue:- A) Embryonic connective tissue:- 1) Mesenchymal connective tissue. 2) Mucous connective tissue. B) Adult connective tissue:- Connective tissue proper:- A- Loose C.T. B-Dense→ irregular → Regular C-elastic→ Dense regular → Dense irregular → Fsenestrated elastic laminae Special C_T:- 1- Reticular C-T. 2- Adipose C-T “unilocular- multilocular. Adult supporting CT 1- Hyaline cartilage. 2- Elastic cartilage. 3- Fibrous cartilage. Ground Substance It is the amorphous substance that fills the space between the cells and the C.T fibers. The amorphous ground substance of connective tissue is a transparent material with the properties of a viscous solution or a highly hydrated thin gel. Its principal constituents are large carbohydrate molecules or complexes of protein and carbohydrate, often called mucopolysaccharides. One of these carbohydrates is hyaluronic acid, composed of glucouronic * Transparent colorless – homogenous, viscous. * Act as lubricant & barrier against penetration of any foreign object.  Connective tissue ---------------------------------------------------------------------------------------------------------  It mainly formed from two classes:- Glycosaminoglycans, glycoprotein Hexamine can be→ glycosmine or galactoseamine Uronicacid can be→ glucouronic or indouronic Connective Tissue Fibers - They are collagen, reticular and elastic fibers - They are distributed irregularly between body organs. - Collagen and reticular developed from protein collagen. - Elastic developed from protein Elastin. Collagen fibers:-  They are the most numerous fibers in the body.  Colorless when fresh.  Take whitish coloration when aggregation of numerous fibers. eg-tendon , eg- apponurosis  In many parts of the body the collagen arranged as array.  It formed from collagen bundles- fibers - fibrils- Tropocollagen molecules  Collagen is inelastic due to molecular configuration. NB- it may be elongated for several percentage if increases tension over the fiber before breaking or cutting point the fiber.  Has tensile strength more than steel.  Average size 50-75nm according to the thickness of collagen bundles.  Longitudinal striation appears in the bundles.  5 types of collagen are recognized:- Chapter 3 --------------------------------------------------------------------------------------------------------- Type I collagen forms striated fibers between 80 and 160 nm in diameter in blood vessel walls, tendon, bone, skin and meat. It may be synthesized by fibroblasts, smooth muscle cells (around blood vessels) and osteoblasts (bone-forming cells). Type II collagen fibers are less than 80 nm in diameter and occur in hyaline cartilage and in intervertebral discs. It is synthesized by chondrocytes (cartilage-forming cells). Type III collagen forms reticular fibers in tissues with some degree of elasticity, such as spleen, aorta and muscle. It is synthesized by fibroblasts and smooth muscle cells, contributes substantially to the endomysial connective tissues around individual muscle fibers, provides a small fraction of the collagen found in skin and occurs in the large collagen fibers dominated by Type I collagen. It may have some function in regulating collagen fiber growth. Type IV collagen occurs in the basement membranes around many types of cells and may be produced by the cells themselves, rather than  Connective tissue --------------------------------------------------------------------------------------------------------- by fibroblasts. Although basement membranes were once regarded as amorphous (like glue), many of them now are thought to be composed of a network of irregular cords. The cords contain an axial filament of Type IV collagen, ribbons of heparin sulphate Chapter 3 --------------------------------------------------------------------------------------------------------- proteoglycan, and fluffy material (laminin, entactin and fibronectin). Type IV collagen occurs in the endomysium around individual muscle fibers. Type V collagen is found prenatally in basement membranes and cultures of embryonic cells. It is synthesized by myoblasts (muscle- forming cells), smooth muscle cells and, possibly, by fibroblasts. Type V collagen has also been found in the basement membranes of muscle fibers, except at the point where muscle fibers are innervated. Type VI collagen is a tetramer of Type VI. It forms a filamentous network and has been identified in muscle and skin. The molecule consists of a short triple helix about 105 nm in length with a large globular domain at each end. Reticular Fiber - Thin fiber 0-5-2um; contain 6-12% hexoses. - Arranged as extended network of anastomosing fibers. - Present in endoneurum of muscle fibers. - In frame work of hemopiotic organs “spleen, bone marrow and lymph node. - Around the paranchymatous organ “liver, kidney and endocrine gland. - Most of reticular fiber is present in inflammatory process, wound healing but it replaced by regular collagen fiber subsequently.  Connective tissue --------------------------------------------------------------------------------------------------------- Elastic Fiber - Is thinner tougher than collagen fiber. - Is wavy, broad, diffusely stained bundles. - Has stretch ability 1½ time than original length, then return back to the original length when stretching removed. - Elastic fiber branched, reunited with one anther. - By E.M. Amorphous central region of elastic surrounded by sheath lo nm tubular fibrils. CONNECTIVE TISSUE CELLS * Mother cells. * Adipose cell * chromospheres * Fibroblast * leukocyte “Blood “ * Fibrocyte * macrophage * Mast cell. * Plasma cells. Chapter 3 ---------------------------------------------------------------------------------------------------------  Connective tissue --------------------------------------------------------------------------------------------------------- Functions of connective tissue cells:- Cell Type Main Product or Activity Main Function Fibroblast, Fibers and ground substance Structural chondroblast, production osteoblast, odontoblast Plasma cell lym- Production of antibodies Immunologic phocyte, (humoral immunity) and of eosinophilic Immuncomptent cells (cell- leukocyte mediated immunity), phagocytosis of antigen- antibody complex Macrophages, Phagocytosis of foreign Defense neutrophilic substance, phagocytosis of leukocyte bacteria Mast cells, Liberation of pharmacologically Release of phar- basophilic leukocyte active substances macologically active sub-stances Adipose cell Storage of neutral fats, heat Energy production reservoir Stem “Mother cell":- - Undifferentiated mesenchymal cell. - Present in loose C.T. - May present in hemopiotic tissue - A ) Fixed in position by reticular network and so called primitive reticular cell B) or leave reticular support & become free. Shape – small branched, large nuclei, poor chromatin. Chapter 3 --------------------------------------------------------------------------------------------------------- Fibroblast: - is the common cell of C.T, responsible for synthesis of C.T fiber & ground substance. - There are two types of cells & several intermediate characteristic features. - The young cell with intense synthesis activity differentiated from the quiescent fibroblast that scattered in the matrix. - Fibroblast known as young cell “ovoid, pale, prominent nucleus, their cytoplasm rich in “R.E.R, developed Golgi apparatus. Fibrocyte Is smaller than fibroblast Has less process with spindle shape Dark, elongated small nucleus. Acidophilic cytoplasm “less R.E.R, GA “ In adult fibroblast rarely undergo meiosis except when damage of CT Chromospheres - Large size cell, contain large branching process - Cytoplasm contains melanin granules. - It present in pigmented layer of retina, meninges, subcutaneous C.T Adipose Cell:- 1- Unilocular “white fat” 2- Multilocular “brown fat” Unilocular “White Fat” - Before storage of the lipid in the cell, it’s shape look like fibroblast. - Fat droplet present in the cytoplasm, then collected together forming one large fat droplet.  Connective tissue ---------------------------------------------------------------------------------------------------------  The cytoplasm appears as rim and the nucleus bulged in the section.  This give fat cell “ signet Ring “  It scattered in the loose CT as single or in group & around blood vessels. Chapter 3 --------------------------------------------------------------------------------------------------------- Multilcocular (brown fat):- - Smaller than unilocular cell - Numerous droplets of fat present in the cytoplasm with centrally located nucleus - The brown color appearance due to cytochrome respiratory pigment. - It present in the intercapsular fat of rodent & hibernating animals and also in new born & human fetus. Mast cell:- - Mast cells play a central role in inflammatory and immediate allergic reactions. - Mast cells contain special cytoplasmic granules which store mediators of inflammation. The extra cellular release of the mediators is known as degranulation - Large ovoid cell - Cytoplasm intensely contains basophilic granules which obscure spherical centrally located nucleus. - It present in many parts of the body & Mast cells settle in connective tissues and usually do not circulate in the blood stream.  Connective tissue --------------------------------------------------------------------------------------------------------- Primary and Secondary Mediators Released by Mast Cells Substance Type of Source Action Mediator Histamine Primary Granule Increases vascular permeability; vasodilation; smooth muscle contraction of bronchi; increases mucus production Heparin Primary Granule Anticoagulant (function in mast cells is not understood) Chondroitin sulfate Primary Granule Function not understood Aryl sulfatase Primary Granule Inactivates Leukotrienes C, thus limiting the inflammatory response Neutral proteases Primary Granule Protein cleavage to activate complement, increasing inflammatory response Eosinophil chemotactic Primary Granule Attracts eosinophils to factor site of inflammation Neutrophil chemotactic Primary Granule Attracts neutrophils to factor site of inflammation Leukotrienes C4 and D4 Secondary Membrane lipid Vasodilator; increases vascular permeability; bronchial smooth muscle contractant Prostaglandin D2 Secondary Membrane lipid Causes contraction of bronchial smooth muscle; increases mucus secretion Function 1) Secrete heparin “anticoagulant “. 2) Secrete SRS- slow reacting substance of anaphylaxis 3) E.C.F.A “eosinophilic chemotactic factors of anaphylaxis. Both SRS-A , Ec.F-A are produced by mast cell but not stored in it. Chapter 3 --------------------------------------------------------------------------------------------------------- 4) Surface of mast cell contain specific receptor for IGE. 5) Not detected by H&E. By Toluidine blue → reddish purple granule “metachromsia “. Plasma Cell (clock face, wheel with spokes):- - Large ovoid cell. - Basophilic, cytoplasm due to richness with R.E.R. Few numbers in C.T - Spherical nucleus, eccentrically located contain compact coarse heterochromatin of equal size resemble wheel with spokes giving the nucleus clock face appearance. - Juxtanuclear Golgi apparatus with centriole occupy region of the cytoplasm which appear pale Function → 1) Antibodies production. 2) Present in inflammation “chronic site of bacterial penetration. Macrophage:- - It derived from precursor cell of bone marrow. - Changed to monocyte in the blood then migrate to C.T. - In C.T become Macrophage. - It may divided & increase in number in the C.T. - When it stimulated increase in size forming epitheloid or fuse together giving giant cell. - Irregular surface with plates, protrusion, indentation. - Well developed Golgi, many Lysosomes, R.E.R.  Connective tissue --------------------------------------------------------------------------------------------------------- - Size 10-30 um. - Kidney shape, oval nucleus eccentrically located. The cells of the Reticulo-endothelial System: Although they are all phagocytic in function, the cells receive different names in different sites. Since they are widely distributed in the body. 1-Macrophages (Histocytes):- in loose connective tissue. 2-Reticular Cells: - in the reticular stroma of bone marrow, spleen and lymph nodes. 3- Littoral Cells: - These were in line of the sinusoids of lymph nodes, spleen and bone marrow. However, E.M has now shown that these sinuses are lined by ordinary endothelium, and that macrophages merely pass in between the endothelial cells by their pseudo-podia to enter into the lumen of sinuses. 4—Von-Kupffer Cells: - are perhaps the true littoral cells which alternate with endothelial cells in lining liver sinusoids. Von-Kupffer cells, have branching processes, and has a large oval nucleus bulging into the sinusoid. These are phagocytic cells which can detach and become washed with the blood stream. With E/M, the cells lining the wall of the sinusoid are not in direct contact with the liver cells, but are separated from them by a "peri-sinusoidal space". This space contains plasma filtered from the sinusoidal blood through tiny holes in the endothelial lining 5-Alveolar Phagocytes: - present in the lung alveoli: These are derived from the septal cells, and are called: (a) Dust Cells: - which accumulate phagocytosis dust or coal particles inside their cytoplasm. Chapter 3 --------------------------------------------------------------------------------------------------------- (b) Heart Failure Cells: - which phagocytosis the R.B.Cs that are extravasated into the alveolar space from congested capillaries in the alveolar walls e.g. in heart failure. 6- Blood Histocytes: present in venous blood. They are detached littoral cells, or wandering connective tissue macrophage. 7- Microglia: - present in the C.N.S. 8- Osteoclasts may be considered a member of this system, on the basis of their functional role in bone removal or resorption. N.B. Neutrophils, and monocytes, though highly phagocytic, are not usually included with this system. Functions of the Reticulo-endothelial System: 1- It acts as a widely distributed defense mechanism. The members of this system are phagocytic cells which phagocytose foreign matter or bacteria that may gain entrance into the tissues, blood, or lymph, 2- Removal of old, worn out R.B.Cs. from the. Circulation (particularly in the spleen, bone marrow, liver). 3- Storage of the iron, to be utilized again in the synthesis of hemoglobin. 4- Important role in immunological response. The reticular.cells in lymphoid organs has a role, in the indirect activation of B lymphocytes. They attract the. Antigen-antibody complex released from the T lymphocytes and deliver the antigen to the B lymphocytes. 5-They help healing of inflammations, by changing to connective tissue fibroblasts.  Connective tissue --------------------------------------------------------------------------------------------------------- Distribution and main functions of the cells of the mononuclear phagocyte system. Cell Type Location Main Function Monocyte Blood Precursor of macrophages Macrophage Connective tissue, lymphoid Production of cytokines, organs, lungs, bone marrow chemotactic factors, and several other molecules that participate in inflammation (defense), antigen Kupffer cell Liver Same as macrophages processing and presentation Microglia Nerve tissue of the central Same as macrophages cell nervous system Langerhans Skin Antigen processing and cell presentation Dendritic Lymph nodes Antigen processing and cell presentation Osteoclast Bone (fusion of several Digestion of bone macrophages) Multinuclear Connective tissue (fusion of Segregation and digestion of giant cell several macrophages) foreign bodies Chapter 3 --------------------------------------------------------------------------------------------------------- TYPES OF CONNECTIVE TISSUES:- 1- Embryonic CT - Composed of irregular shape mesenchymal cells with process. - May be contact the adjacent cells. - Mitotic division observed. - No C-T fibers were observed - Ground substance fills the intracellular space. Mesenchyme is the precursor of all adult cells, tissue, organs of mesodermal origin “bone, cartilage, C.T and muscles. 2-Mucous CT (gelatinous) each of these sections through the umbilical cord contains two umbilical arteries and one larger diameter umbilical vein. Surrounding the vessels is an abundant mucous connective tissue with scattered fibroblast cells and randomly arranged collagen fibers in a large amount of ground substance. Observe fibroblasts in full face (whole nucleus and nucleoli are visible)or in side profile (cell appears fusiform in shape and shows little nuclear detail). There is more ground substance and fewer fibers in mucous connective tissue than in adult connective tissue. Mucous tissue in the umbilical cord is called Wharton's jelly. - Polymorphic interconnected process and vacuolated cytoplasm. - Some cells look like macrophage, fibroblasts are present.  Connective tissue --------------------------------------------------------------------------------------------------------- - Viscous gel like ground substance fills the space. - It noticed in umbilical cord and comb and wattle of poultry. Adult connective tissue:- Chapter 3 --------------------------------------------------------------------------------------------------------- -Loose CT (Areolar):- Areolar tissue (loose connective tissue proper) forms the stroma or framework of many organs and surrounds blood vessels and nerves. Compare the morphology of the thick collagen fibers with the thin branched elastic fibers. Identify the spindle- shaped fibroblasts with their pale, oval euchromatic nuclei. Numerous cytoplasmic granules and pale-staining spherical nuclei of mast cells. Ground substance has been lost during fixation leaving open spaces throughout this tissue. * Fill the space between fibers, Muscle sheath, and support epithelium from layer of endothelial sheath of blood vessels. It also found in the papillary layer of dermis, hypodermis, serosal lining of peritoneum, pleural cavity, and glands. Dense irregular Fibrous C.T. :- This consists the same as loose CT except. The ground substance occupies little space and the fibers (mostly collagen) in this kind of tissue are not oriented predominantly in one direction.  Connective tissue --------------------------------------------------------------------------------------------------------- - Collagen bundles are predominant in the ground substance. - The fibroblasts are dominant. - Less flexible and resist stress due to collagen bundles. - Known irregular due to non orientation of the collagen fibers. - Present in skin dermis, submucosa of the digestive tract, capsule of spleen, lymph node and ganglia. Dense regular C.T :- Described as dense irregular except collagen bundles arranged in oriented manner. Present in the tendon “white color due to richness of collagen closely backed bundles of collagen Chapter 3 --------------------------------------------------------------------------------------------------------- separated by intercellular substance. fibrocyte has elongated nucleus parallel to the fiber collagen bundles of the tendon “ primary bundles “ enveloped by loose C.T & blood vessels and nerve. Finally enclosed by dense C.T Sheath. Elastic CT This type of C.T mainly formed from elastic C.T and found in three forms. Dense regular Elastic C.T:- Elastic fibers arranged in cords parallel to each other & connected by loose C.T e.g funicular part of ligamentum nuchiae. Dense irregular elastic C.T:- The elastic fiber closely backed & irregularly anatomized leaving pores in some parts of the lamellae. e.g lamellar part of the Ligamentum nuchiae. Fenestrated elastic lamina (membranes) Elastic fibers arranged as zigzag, flatten membrane provided by pores in many parts. They are attached to each other by fine collagen fiber. e.g. Large artery (Aorta). SPECIAL CONNECTIVE TISSUE Reticular Tissue:- Specialized C.T. Provide the architecture frame work of hemopiotic organs Also present in all paranchymatous organs.  Connective tissue --------------------------------------------------------------------------------------------------------- It consists of reticular fibers & reticular cells. Reticular cell → elaborate fine matrix of branched reticular fiber then dispersed a long matrix & unsheathed the reticular fiber & ground substance with cytoplasmic process. Mononuclear phagocytic process. Mononuclear phagocytic cell also dispersed along the trabeculae. Adipose C.T:- In adult mammals, the major bulk of adipose tissue is a loose association of lipid-filled cells called adipocytes, which are held in a framework of collagen fibers. In addition to adipocytes, adipose tissue contains stromal- vascular cells including fibroblastic connective tissue cells, leukocytes, macrophages, and pre- adipocytes (not yet filled with lipid), which contribute to structural integrity. The lipid droplets in adipose tissue can be unilocular and/or multilocular. Unilocular cells contain a single large lipid droplet which pushes the cell nucleus against the plasma membrane, giving the cell a signet-ring shape. Unilocular cells, characteristic of white Chapter 3 --------------------------------------------------------------------------------------------------------- adipose tissue, range in size from 25 to 200 microns. Mitochondria are found predominately in the thicker portion of the cytoplasmic rim near the nucleus. The large lipid droplet does not appear to contain any intracellular organelles. Multilocular cells, typically seen in brown adipose tissue, contain many smaller lipid droplets. A cell in brown adipose tissue may reach a diameter of 60 microns and the lipid droplet within the cell may reach 25 microns in diameter. As mentioned above, the brown color of this tissue is derived from the cells' rich vascularization and densely packed mitochondria. These mitochondria vary in size and may be round, oval, or filamentous in shape. White adipose tissue is not as richly vascularized as brown adipose tissue, but each adipocyte in white adipose tissue is in contact with at least one capillary. This blood supply provides sufficient support for the active metabolism, which occurs in the thin rim of cytoplasm surrounding the lipid droplet. Blood flow to adipose tissue varies depending upon body weight and nutritional state, with blood flow increasing during fasting. Adipocytes are considered to originate from fibroblast-like precursor cells that differentiate into adipocytes under the appropriate stimulatory conditions (described below). The precursor cells do not possess any morphological or enzymatic marker that can be used to determine whether they will become adipocytes. The criteria used to identify adipocytes depend upon lipid accumulation within the cell after proliferation has stopped, making early identification of adipocytes difficult. The size of adipose tissue mass is a function of both adipocyte number and size. An increase in adipose tissue mass can occur by hyperplastic growth, which is an increase in the number of adipocytes. This increase in number occurs primarily by mitotic activity in precursor cells.  Connective tissue --------------------------------------------------------------------------------------------------------- SUPPORTING TISSUE  Type of C.T in which their intercellular materials have rigidity & can resist stress. The cartilage have smooth surface. The cartilage supports the soft tissue. The cartilages facilitate gliding of bone. The cartilage essential for bone growth, before, after birth The cartilage contains numbers of intracellular material called:-  Cartilage matrix.  Lacuna cavity.  Chondrocytes. Blood supply: - Devoid of bloody supply but nourished through diffusion from adjacent structure or via synovia from synovial fluid. Types 1- Hyaline →most common & contain moderate amount of collagen fiber. 2- Elastic→ numerous amount of elastic and small amount of collagen fibers. 3- Fibrous → net work of coarse collagenous fiber. Perichondrium:- Special capsule like sheath of dense irregular CT contain blood supply & surround cartilage. HYALINE CARTILAGE - Fresh hyaline is bluish white, translucent. - It acts as temporary skeleton for the embryo until the skeleton is developed. - It present between epiphysis & diaphysis of long bone “epiphyseal plate which responsible for growth of long bone. Chapter 3 --------------------------------------------------------------------------------------------------------- Site→  Wall of respiratory passage  Ventral end of ribs.  In articular cartilage. Matrix→ 40% collagen fiber II (not as bundle but thin meshwork) in amorphous intra cellular substance & it can’t be visible due to.  It present in form of fibrils which had microscopic appearance.  Its refractive index like that of the amorphous substance. Perichondrium:- - All hyaline covered with dense layer of C.T except “articular cartilage” - It responsible for growth & maintenance of cartilage. - It contains collagen fiber & cell similar to fibroblast in inner surface cells differentiated to chondroblast. Chondrocyte →  It present in the periphery of the cartilage.  Round in adult, flat in young.  It may arranged in group of 8 cells from mitotic division of one chondrocyte” isogenous group”  Chondrocyte:- - Secrete type II collagen & glycosaminoglycans.  Connective tissue --------------------------------------------------------------------------------------------------------- - During processing of the sample, the chondrocyte shrink & appear irregular. - It synthesis all matrix components of the cartilage. - Its function depends on proper hormonal balance because of cartilage devoid of blood vessels so chondrocyte respire under low O 2 tension so the width maximum of cartilage is limited. E.M - Round or oval nucleus contains several nucleoli. - Juxtanuclear cell center with pair of centriole & well develop GA. - Elongated mitochondria, lipid droplets and glycogen. Growth of cartilage:- I- interstitial growth → mitotic division of chondrocyte. II appositional growth → due to differentiation of peripheral cell of Perichondrium. In both case newly formed matrix & collagen fibrils. NB - In articular cartilage * No appositional growth due to absence of Perichondrium. ELASTIC CARTILAGE Site: -Auricle of ear epiglottis External auditory canal cuneiform cartilage of larynx Eustachian tube Structure  Appear yellowish coloration.  Mainly appositional growth.  Matrix has collagen type II, elastic fiber. Perichondrium, chondroblast, chondrocyte. Chapter 3 ---------------------------------------------------------------------------------------------------------  More great opacity & elasticity.  Ground substance is obscured by net work of the elastic fibers.  Growth by appositional growth FIBRO CARTILAGE  Connective tissue --------------------------------------------------------------------------------------------------------- This Type between Dense C.T & hyaline cartilage. No Perichondrium observed in this type of cartilage. - Matrix is acidophilic because it contain numerous coarse collagen type I - Chondrocyte as single or isogenous group & also arranged in column. - Amorphous matrix is not abundant - Contain equal amount of chondratin sulphate and dermatin sulphate. * Site - Inter vertebral disk. - Symphsis pubica. - At attachment of certain ligament to bone. * Growth - Differentiation of dense C.T cells to chondroblast then to chondrocyte. NB→ This type is transition form between hyaline & elastic cartilage Gradual transition can observed in adult & embryo General Characteristics of Bone in Comparison to Cartilage: Bone Cartilage -It is a solid weight-bearing tissue, -It is rigid weight-bearing tissue, which is inflexible i.e. it breaks on but shows some degree of bending. flexibility. -The matrix is solid because of -The matrix is rigid due to deposition of calcium salts. presence of chondroitin sulphuric -Bone cells "osteocytes" are present acid. singly inside lacunae. -Cartilage cells "chondrocytes" are -Osteocytes intercommunicate by their present singly or in groups inside Chapter 3 --------------------------------------------------------------------------------------------------------- thin cellular processes. lacunae. -The lacunae intercommunicate by -Chondrocytes do NOT canaliculi communicate. -Bone is vascular. It is permeated by - Lacunae do NOT Haversian and Volkmann's canals and communicate. canaliculi which carry blood vessels - Cartilage is from the periosteum to the vicinity of NONVASCULAR; but Chondrocytes the cell. receive nourishment by diffusion -Osteocytes cannot divide. from blood vessels in the Perichondrium. Cartilage Types, Characteristics and Locations Type of Identifying Perichondrium Location Cartilage Characteristics Hyaline Type II collagen, Perichondrium present in Articular ends of long basophilic matrix, most places. Exceptions: bones, nose, larynx, chondrocytes usually Articular cartilages and trachea, bronchi, arranged in groups epiphyses ventral ends of ribs Elastic Type II collagen, Perichondrium present Pinna of ear, walls of elastic fibers auditory canal, auditory tube, epiglottis, cuneiform cartilage of larynx Fibrocartilage Type I collagen, Perichondrium absent Intervertebral disks, acidophilic matrix, articular disks, pubic chondrocytes symphysis, insertion of arranged in parallel some tendons rows between bundles of collagen, always associated with dense regular collagenous connective tissue or hyaline cartilage  Connective tissue --------------------------------------------------------------------------------------------------------- BONE It is special type of C.T composed of intercellular calcified material. The bone characterized by its rigidity. It covered by periosteum and lined by endosteum Bone Matrix Composed of organic mater or osteoid which represent about 40% of dry bone weight and inorganic mater ( bone minerals) which represent 60% as calcium, phosphate , sodium , magnesium , potassium and etc. It also contains collagen fibers type I which represent 90% embedded in ground substances. Bone matrix contains cells (Osteocyte, osteoclast and osteoblast.) Endosteum: - Is the lining of the bone cavity. It consists of layer of osteogenic cells Periosteum. It is CT capsule that cover the whole bone except articular surface. It consists of outer fibrous layer and inner osteogenic layer BONE CELLS Osteogenic cells - Small oval cells with pale cytoplasm and oval nucleus - It located in the endosteum and periosteum of the bone - Its also called osteoprogenitor cells(mesenchymal in origin ) Osteoblast - Located at surface of the bone tissue.  Chapter 3 --------------------------------------------------------------------------------------------------------- - Responsible for synthesis of bone matrix (osteoid). - It arranged side by side and seen in endosteum and periosteum - Large round branched cell with basophilic cytoplasm and eccentric nucleus - Well developed r.E.R, prominent Golgi apparatus and many ribosomes. - Have cytoplasmic process & contact the neighbor osteoblast. - When osteoblast surrounded with newly formed matrix it referred as teoute and lacuna, canaliculi are present. - Large round nucleus contains dispersed chromatin. Osteocyte - Flat – almond shape. - The cells are smaller than osteoblast and of less basophilic cytoplasm with large dark centrally located nuclei - Reduced number of r.E.R, Golgi apparatus and mitochondria - More condensed nuclear chromatin. - Found in mineralized bone matrix. - Canaliculi radiate from the lacunae. - It contain protein, lipoprotein. - the Osteocyte is the main cell in the mature bone and maintain its matrix - It also responsible for exchange of nutrients and waste product via its branches which connect the canaliculi. Osteoclast - Large motile, branched cell. It reached to 150um in diameter. - the cell have 6 : 50 nuclei.  Connective tissue --------------------------------------------------------------------------------------------------------- - It located in Howship lacunae. - It originate from osteoprogenitor cell - Recently “ derived from the fusion of blood monocytes so it considered as one the macrophage cells L.M → acidophilic cytoplasm and multinucleation up to 50 nuclei. E.M → Surface of osteoclast facing matrix is folded subdivided into compartment called brush border ( ruffled border) - Numerous free polysomes. - Some R.E.R, abundant Mitochondria. - Well developed GA. Great Number of lysosome. Function - Osteoclast called bone eating cell ( resorption cell), in which the osteoclast secrete enzyme ( in the cavity between bone and the brush border) which dissolve the mineralized matrix of the bone and release minerals - It also responsible for bone remolding when any disturbance in the shape of the bone during growth so it called ( bone eating cell) TYPES OF BONE COMPACT BONE SPONGY BONE Compact bone:- - Solid mass found in the long bone shaft Chapter 3 --------------------------------------------------------------------------------------------------------- - It characterized by regular bone lamellae - The bone lamellae consists of osteocyte inside lacunae and canaliculi embedded in the calcified collagen fibers - The bone lamellae are concentrically arranged around vascular channel called Haversian canal - This orientation form Haversian system ( osteon) - each Haversian system consists of 5-20 bone lamellae  Connective tissue --------------------------------------------------------------------------------------------------------- The blood supply and nerves inter the canal and run longitudinally - The blood vessels in the Haversian system are connected to each other and to the periosteum and the bone marrow via transverse canal (Volkmann's canal). - The bone lamellae run under the bone endosteum called internal circumferential lamellae. - The bone lamellae run close to the bone periosteum called external circumferential lamellae. - The bone lamellae run irregularly between the Haversian system called interstitial lamellae. - The collagen fibers which run from the periosteum to the Haversian system called sharpey's fibers. Spongy bone (cancellous) - Found at the ends of the long bones, in the center of flat and irregular bone - It is formed from branching irregular bone lamellae - No Haversian system - The nourishment of the osteocytes via the diffusion through the bone marrow - The bone marrow appears as irregular cavities between bone trabecula. Chapter 3 --------------------------------------------------------------------------------------------------------- Compact Bone Cancellous Bone 1-NAKED EYE EXAMINATION It looks solid, like ivory, with no -It looks spongy, with many holes apparent holes, (hence the name separated by irregular bars and "compact") trabeculae. (hence the name "spongy") 2-SITES : -It is present in: 1) epiphysis of long It is present in: 1) shafts of long bone, bones, 2) young embryonic bone, 3) 2) outer and inner tables of flat bones ribs, bodies of vertebrae, and sternum. of skull, 3) outer covering of vertebrae, ribs, etc. 3-STRUCTURE : The bone lamellae are deposited The bone lamellae are deposited in the in a regular pattern : form of irregularly arranged bars or a) Outer circumferential lamellae: are trabeculae, which branch and anasto- subperiosteal, and parallel to the outer mose. The bone trabeculae are circumference of the bone. separated by bone marrow spaces of b) Concentric lamellae: are concentric irregular shape and size. layers around Haversian canals, form- ing Haversian systems. c) Interstitial lamellae: present in between Haversian systems. d) Inner circumferential lamellae: present under the endosteum, parallel to the circumference of the medullary bone cavity, which contains the bone marrow.  Connective tissue --------------------------------------------------------------------------------------------------------- BLOOD It is consists cells and plasma. Plasma:- It is the liquid intercellular material which gives the blood its fluid properties. Chemically plasma consists of:- Water 91 – 92 % ; Protein 7.8 % protein globulin, albumen, fibrinogen ; other salts 1-2 %. Electrolytes, non protein nitrogenous sub. Regulatory substance, blood gases. BLOOD CELLS 1- R.B.Cs 2- blood platelets 3- W.B.Cs * R.B.Cs (Red Blood Corpuscles):- - Biconcave disk like, non nucleated. Chapter 3 ---------------------------------------------------------------------------------------------------------  Connective tissue --------------------------------------------------------------------------------------------------------- - Have phenomena of Rulex formation. - Its size and number goat 1 – 4 um 7 million. Dogs 7 um 14 million. - Life span about 120 day. - Old cells removed by the reticuloendothelial cells. - New R.B.Cs generated in the myeloid tissue. E.M. - Mature R.B.Cs have no organelles. - No nuclei, Golgi, Mitochondria, centriole. - Interior of the cell consists of fine granular material. - Plasma membrane surrounds the cell. - Specific component are hemoglobin. Species Difference in R.B.Cs * Camel & lama (Tylopoda) Biconcave, small elliptical, no nucleus. * Birds, reptiles and fish Biconvex, medium size, oval and nucleated * Amphibian (frog) Biconvex, large, ovoid and nucleated. Blood Platelets - Small cytoplasmic fragments. - 350000 – 500000 in mammals and 2 – 14u in size. Chapter 3 --------------------------------------------------------------------------------------------------------- - 100,000 in Bird (nucleated (. - Life span 5 – 9 days. - It originate from the megakaryocyte of the bone marrow E.M.  Cells have well developed cell coat & surrounded by plasma membrane.  It contains 2 types of granules. (1) Alpha lysosmal granules. (2) Very dense granules.  Two system of tubules (1) One connected to the surface. (2) One contain electron dense material, it also contain microtubules & filament. Two definite areas are seen:- (1) The chromomere “granulomere → intensely stained area. (It contain the microtubules and the filaments) (2) hyalomere→ lightly stained area.( it contain the tubules , dense granular material and other components). W.B.Cs Granular A granular 1-Neutrophils 1-Lymphocyte 2-Eosinophils 2-Monocyte 3-Basophils  Connective tissue ---------------------------------------------------------------------------------------------------------  Number of W.B.Cs are few up to 10000 cells  Life span are few days Neutrophils:- - Their size 10- 12 um and represent 60 – 70 of total W.B.Cs. - Nucleus is lobulated 2 – 5 lobules which are connected by fine chromatin strand. - The female Neutrophils characterized by small oval nuclear body bar body are seen attached to the main lobe. - Cytoplasm is pale grayish contain fine dust like granule. - Immature neutrophils called “Band or juvenile neutrophils which has horse shoe shape nucleus. - Has neutrophilic granules → 80%. (Small, contain bactericidal substance & phosphate). - Has azurophilic granules → 20%. (Oval dense like & contain hydrolytic & peroxidase enzyme Function 1-Highly phagocytic “microphage” 2- They share in the pus formation “died neutrophil plus infected tissue 3- They attract the monocyte to the site of infection 4- They stimulate the bone marrow → give neutrophils Eosinophil:- Its size 12- 15 um and represent 1-5% of the total W.B.Cs Chapter 3 ---------------------------------------------------------------------------------------------------------  Nucleus is typically bilobed. - The compact hetero chromatin is chiefly adjacent to the nuclear envelope, where euchromatin chiefly present in the center.  Cytoplasm is loaded with large refractite granules which stain with eosin. - It only contain space which represent the membranous organelles expect numerous large elongated granules Function:- 1- Contain Histaminase enzyme destroy histamine sulphatase destroy SRS-A as in mast cells. 2- Accumulate in the site of allergy. 3- It attracted to the site of allergy by eosinophil chemotactic factor) released by mast cells. 4- They have very low powerful phagocytic function “it destroy phagocytose Antigen – Antibody Complex. Basophil:- Its size 8- 10um and represent 1/2 – 1% Total W.B.Cs. Nucleus obscured by large granules. E.M. Large lobulated nucleus. Heterochromatin chiefly in peripheral location.  Connective tissue --------------------------------------------------------------------------------------------------------- Euchromatin centrally located. Cytoplasm is coarse basophilic metachromatic granules which stain darker than the nucleus. Function  Cell secretes heparin, serotonin and histamine.  Basophile related but not identical to mast cell of C.T Chapter 3 --------------------------------------------------------------------------------------------------------- AGRANULOYTE Small Lymphocyte:- - Mature 6-9um. , represent 20-30% of total W.B.Cs. - The nucleus is large, spherical, dense, No organelles except Ribsome. - Non granular cytoplasm with thin pale blue. - They are antibody producing cell, they are covered by microvilli. LARGE LYMPHOCYTE - Less mature cell 12-15 um. - They divided to give medium, small lymphocyte. - The nucleus → smaller, less dense and indented. - Cytoplasm → more abundant, pale blue, non granular - Azurophilic granules may be seen at nuclear indentation. * Antibody producer. Lymphocytes are highly motile → head contain nucleus. While → tail contain rest of cytoplasm“look like Tennis racquet “ - Two types of lymphocytes are known B &T  Connective tissue --------------------------------------------------------------------------------------------------------- B lymphocyte T lymphocyte Ratio 25% 75% Origin Bone marrow Thymus Life span 3 month years Types B memory Memory, helper and killer( Cytotoxic) Function Humeral immunity Cell mediated Monocyte They are mature cell 15-20um in size and represent 5% of total W.B.Cs. Nucleus → oval or horse shoe or kidney shape, eccentric position. Cytoplasm → more abundant, pale grayish blue. Fine dust like azurophilic granules usually present. - The cell membrane show pseudopodia Function → - Phagocytic cells capable of migrating by amoeboid movement into the surrounding CT change to macrophage and stay for 3 day in the blood. BONE MARROW - It is the main source of myeloid cells after birth. - It presents cavities of spongy bone and medullary canal of long bone. - 2 types of bone marrow are recognized. 1) Red “Haematogenous “Active “that due to hemoglobin content. 2) Yellow “inactive “that due to high contents of fat. Chapter 3 --------------------------------------------------------------------------------------------------------- Bone marrow consists of:- 1) Reticular stroma “ blood sinusoid “ fixed element “ 2) Free cells “developing blood cells. 1- Reticular stroma - Reticular framework contains arteriole, venule, and blood sinusoid. - It also contain variety of cells that are fixed in the stroma & called (Fixed cells ) - Also free cell present in the stroma “immature “& it develop within the meshes then inter blood stream when mature. - Blood sinusoid present in the stroma & lined with perforated endothelial cells & supported with reticular tissue.  Connective tissue --------------------------------------------------------------------------------------------------------- - Pseudopodia of monocyte present squeezed between endothelial cells to project in to the lumen. - Fixed stromal cells include (1) Fat cells with constitute main bulk of yellow marrow. (2) Reticular cells - Large branched cell with pale cytoplasm. - Pale nucleus branches of it connected together forming reticulum in which free cells developed in its meshes. - Reticular cells produce reticular fiber and some of them are phagocytic while other has indirect role in immunological reaction. 3) Fibroblast which support blood vessels. 4) Macrophage derived from monocyte. 5) Osteogenic cells lined bone trabecula, derived from the pericyte of periosteal bud. 6) Endothelial cell derived from endothelium of blood vessels of the periosteal bud that lined blood vessels and sinusoid. 2-Free Cells These are developing blood cells in various stage of development. - They present in meshes of reticular stroma. - They derived from common ( Ancestral cell ) called colony forming unit ( C.F.U ) - (UMC) derived from undifferentiated primitive mesenchymal cell in the blood islands of yolk sac in embryo - It is very difficult to detect them because they represent 0.1% of marrow cells. Chapter 3 --------------------------------------------------------------------------------------------------------- - They discovered recently and they are resemble lymphocyte but differ in : (1) Slightly larger 7 – 10 um (2) More irregular in shape. (3) Round nucleus no indentation and fine chromatin. (4) Cytoplasm contains freer ribosome, more mitochondria, ill developed Golgi and few R.E.R. (5) They are undifferentiated pluripotent cells which capable of division & differentiation to give various subline of blood cells. BLOOD PLATELETS Platelets originate in the bone marrow by fragmentation of cytoplasm of megakaryocyte Megakaryoblast → give megakaryocyte → by fragmentation→ platelets. Megakaryoblast → - large ovoid or kidney shape nucleus. - Numerous nucleoli. - Homogenous basophilic cytoplasm. - 15-50 um Megakaryocyte - Giant cell 35 – 150 um - Irregular lobulated nucleus - Coarse chromatin. - No visible nucleoli. - Light basophilic cytoplasm. - Numerous azurophilic granules which form chromere of the platelets  Connective tissue --------------------------------------------------------------------------------------------------------- - Light basophilic cytoplasm.