| Talk about the activity of cartilage tissue. | High mitotic activity, actively synthesis macromolecules of ECM, chondroblast differentiate and acquire characteristics of adult or mature cartilages and become chondrocytes |
| How is does cartilage tissue differ? | by composition of their ECM: nature and proportions of ground substances and different types of fibers, cellular density is inversely proportional to the thickness of the cartilage, three groups: Hyaline cartilage, Elastic cartilage ,and fibrous cartilage. |
| What is cartilage tissue? | Specialized CT, part of skeletal tissues which are specialized CT whose ground substances vary depending on applied pressure, from semi-solid to solid state, (bone-cartilage) |
| How do cartilage tissues differentiate? | They arise from embryonic mesenchyme, (clusters differentiate to form chondroblast) |
| What are the components of cartilage tissue? | Chondrocytes+ cartilaginous ECM, no blood, lymphatic vessels and nerve fibers. |
| Talk about the chondrocytes. | Differentiate from chondroblast, spherical or rounded send very short and thin extentions to ECM. Large spherical central nucleus with one or more nucleuoles, basophilic cytoplasm containing usual cell organelles (RER and free ribosomes), enclosed in small lacunae without a wall, synthesize all macromolecules of ECM, maintain their integrity by ensuring their renewal. |
| Talk about cartilage ECM. | Appears homogenous in EM, consists of water, mineral salts, GAGs proteoglycans, (aggrecan; hyaluronic acid+ proteins) ,collagen fibers especially type II, and structural glycoproteins (chondronectin, chondrocalcin, fibronectin, tenascin,) also contains nutrients, metabolites, and molecules resulting from chondrocyte activity.
Highly basophilic, collagen gives strength and resistance to compression. and deformation |
| What is the perichondrium? | Surrounding layer of cartilage (except articular cartilage and fibrocartilage) separating them from CT, vascularized play a role in nutrition, growth maintanance of cartilage and repair, two layers. |
| Talk about the two layers of perichondrium. | - Chondrogenic layer (deep layer formed of loose CT, poorly vascularized, makes connection with cartilage rich in cells and deepest mesenchymal cells and fibroblast differentiate into chondroblasts that synthesize cartilage ECM.
-Tediniform layer: composed of fibrous dense irregular CT (collagen and elastin and dispersed fibroblasts), highly vascularized, fibrous layer of perichondrium. |
| Talk about hyaline cartilage. | Most common, chondrocytes are in small amounts, found in lacunae and dispersed in ECM rich in ground substances, not fibers, constitutes largest part of fetal skeleton and transforms to bones in children and adolescents.
two types: Non- articular (persists in trachae and bronchi)
articular (selectively in joints of long bones, provides motility, prevents friction with synovial fluid, rigid but also deformable, ensure harmonious distribution of stress on all area. |
| Talk about elastic cartilage. | modification of Hyaline one, rich in chondrocytes, contain large lipid inclusions, numerous elastic bundles, in addition to type II collagen, forming a network around the chondrocyte, surrounded by perichondrium and grows by apposition and interstitual growth, found in places where flexibilty is needed, supports slight deformation, in nose and oricule of ears. |
| Talk about fibrohcartilage. | devoid of perichondium, growth by interstitial growth, not a modification of hyaline, devoid of lipid inclusions, surrounded by ground substances without fibers, ECM fibers are of types I and II, abundant and grouped into bundles and oriented towards force of tension, adapted to withstand high friction while keeping flexibility, intervertebral disks and articular menisci of knees. |
| Talk about nutrition of cartilage. | devoid of blood and lymphatic vessels, nourished by diffusion of molecules into their ECM from capillaries of outer layer of perichondrium,but hyaline and fibro cartilage are nutritioned by synovial fluid and exchanges wit subchondral bones. |
| Talk about interstitial growth of cartilage. | Obsereved in fetus and post-natal growth of long bones, chondroblasts and chondrocytes are divided by mitosis and two or more daughter cells are remained in same lacuna, ensuring expansion of internal mass and synthesis of ECM gets daughter cells apart.
May be linear (same direction mitosis axial isogenic group) and increase in size (epiphyseal group) or circular (radial isogenic group) and increases in girth. rare in adults. |
| Talk about appositional or perichondral growth of cartilage. | during fetal development, proliferation and progressive differentiation of mesenchyme and fibroblasts into chondroblasts , functional chondrocytes secrete ECM cartilage, apposition of succssive layers of cartilage on surface of preexisting cartilage that grows in thickness. |
