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Histology of Hyaline cartilage: Shotgun Histology

📌 𝐅𝐨𝐥𝐥𝐨𝐰 𝐨𝐧 𝐈𝐧𝐬𝐭𝐚𝐠𝐫𝐚𝐦:-   / drgbhanuprakash   📌𝗝𝗼𝗶𝗻 𝗢𝘂𝗿 𝗧𝗲𝗹𝗲𝗴𝗿𝗮𝗺 𝗖𝗵𝗮𝗻𝗻𝗲𝗹 𝗛𝗲𝗿𝗲:- https://t.me/bhanuprakashdr 📌𝗦𝘂𝗯𝘀𝗰𝗿𝗶𝗯𝗲 𝗧𝗼 𝗠𝘆 𝗠𝗮𝗶𝗹𝗶𝗻𝗴 𝗟𝗶𝘀𝘁:- https://linktr.ee/DrGBhanuprakash Histology of Hyaline cartilage: Shotgun Histology Cartilage: There are three types of cartilage Hyaline - most common, found in the ribs, nose, larynx, trachea. Is a precursor of bone. Fibro- is found in invertebral discs, joint capsules, ligaments. Elastic - is found in the external ear, epiglottis and larynx. Hyaline cartilage --------------------------- This type of cartilage has a glassy appearance when fresh, hence its name, as hyalos is greek for glassy. It looks slightly basophilic overall in H&E sections. Hyaline cartilage has widely dispersed fine collagen fibres (type II), which strengthen it. The collagen fibres are hard to see in sections. It has a perichondrium, and it is the weakest of the three types of cartilage. Hyaline cartilage develops, like other types of connective tissue, from mesenchymal cells. From about the fifth foetal week precursor cells become rounded and form densely packed cellular masses, chondrification centres. The cartilage-forming cells, chondroblasts, begin to secrete the components of the extracellular matrix of cartilage. The extracellular matrix consists of, ground substance (hyaluronan, chondroitin sulfates and keratan sulfate) and tropocollagen, which polymerises extracellularly into fine collagen fibres. Tropocollagen type II is the dominant form in collagen fibres of almost all types of cartilage. As the amount of matrix increases the chondroblasts become separated from each other and are, from this time on, located isolated in small cavities within the matrix, the lacunae. Concurrently the cells differentiate into mature cartilage cells, chondrocytes. Growth occurs by two mechanisms -------------------------------------------------------- Interstitial growth - Chondroblasts within the existing cartilage divide and form small groups of cells, isogenous groups, which produce matrix to become separated from each other by a thin partition of matrix. Interstitial growth occurs mainly in immature cartilage. Appositional growth - Mesenchymal cells surrounding the cartilage in the deep part of the perichondrium (or the chondrogenic layer) differentiate into chondroblasts. Appositional growth occurs also in mature cartilage. Like all protein-producing cells, chondroblasts contain plenty of rough endoplasmatic reticulum while they produce matrix. The amount of rough endoplasmatic reticulum decreases as the chondroblasts mature into chondrocytes. Chondrocytes fill out the lacunae in the living cartilage. The matrix appears structureless because the collagen fibres are too fine to be resolved by light microscopy (~20nm), and because they have about the same refractive index as the ground substance. Collagen accounts for ~ 40% of the dry weight of the matrix. The matrix near the isogenous groups of chondrocytes contains larger amounts and different types of glycosaminoglycans than the matrix further away from the isogenous groups. This part of the matrix is also termed territorial matrix or capsule. In H&E stained sections the territorial matrix is more basophilic, i.e. it stains darker. The remainder of the matrix is called the interterritorial matrix. Fresh cartilage contains about 75% water which forms a gel with the components of the ground substance. Cartilage is nourished by diffusion of gases and nutrients through this gel. #histologyofhyalinecartilage #hyalinecartilagehistology #hyalinecartilage #shotgunhistology