Cartilage Notes PDF

Histology Lecture Notes Dr. Shaimaa Kashef Cartilage At the end of this chapter, the student will be able to: 1. Define and describe the structure and functions of the different types of cartilage 2. Classif...

Histology Lecture Notes Dr. Shaimaa Kashef Cartilage At the end of this chapter, the student will be able to: 1. Define and describe the structure and functions of the different types of cartilage 2. Classify, compare, and contrast the organization, location, and function of the three different types of cartilage 3. Differentiate between the different types of cartilage 4. Handle the microscope efficiently and draw and label the structure of cartilage seen by light and electron microscopy during practical classes. Definition: The cartilage is a firm, flexible, and strong connective tissue. It like other connective tissues, is formed of cells, fibers, and intercellular matrix. It is an avascular connective tissue and requires the nourishment of the chondrocytes by diffusion of nutrients from the blood vessels found in the perichondrium. It is a dense irregular connective tissue sheath overlying most cartilage found in the body. It contains an outer fibrous layer and an inner cellular layer (chondroblasts). The only place where a perichondrium does not exist is within joint capsules (ex: joints of the knee). Structure of cartilage 1- Cartilage cells: Chondroblasts and chondrocytes. 2- Extracellular matrix: a- Fibers. b- Ground substances. 1 Histology Lecture Notes Dr. Shaimaa Kashef 1-Cartilage cells: Chondroblasts Chondrocytes Site They present under the They present within spaces perichondrium, parallel to called lacunae either single the outer fibrous layer or in-groups called isogenic group or cell nest. (up to 8 cells in the same lacuna). Structure They are oval or spindle in Their cytoplasm is less shape with basophilic basophilic and their nuclei cytoplasm and pale nucleus. are deeply stained Chondroblasts change into chondrocytes when they are trapped inside lacunae. Function They synthesize proteins They are less active than and fibers of the matrix chondroblasts Figure (1): Chondroblasts and chondrocytes https://shorturl.at/dtqy1 2 Histology Lecture Notes Dr. Shaimaa Kashef 2-Extracellular matrix: a- Fibers: Hyaline cartilage contains type II collagen while elastic cartilage contains an abundant network of elastic fibers in addition to collagen fibers. Fibrocartilage and the perichondrium, contain type I collagen fiber. b- Gound substance It is basophilic and composed of proteoglycans and glycoprotein Figure (2): Histological structure of the cartilage https://shorturl.at/j97YM 3 Histology Lecture Notes Dr. Shaimaa Kashef Types of cartilage There are three types of cartilage: A-Hyaline cartilage (Fig. 3) - It is the most common type of cartilage in the body - The matric contains collagen fibers (II) which is not seen by L/M because they have the same refractive index of the matrix - Sites: costal cartilage, articular cartilage and trachea Figure (3): Hyaline cartilage https://shorturl.at/WQTiB B- Elastic cartilage (Fig. 4) Elastic cartilage is the most flexible cartilage. It supports parts of your body that need to bend and move to function. It is identical to hyaline cartilage except that its matric contains an abundant network of elastic fibers. Si:tes Ear pinna. 4 Histology Lecture Notes Dr. Shaimaa Kashef Figure (4): Elastic cartilage https://shorturl.at/WQTiB C- Fibrocartilage - It has no perichondrium - It is intermediate between dense connective tissue and cartilage because its matrix contains many bundles of collagen fibers type one. - The chondrocytes inside lacunae are usually present in rows surrounded by collagen bundles in great amounts Sites: intervertebral discs Figure (5): Fibrocartilage https://shorturl.at/WQTiB 5 Histology Lecture Notes Dr. Shaimaa Kashef Test your self Q1. MCQ 1) Which one of the following types of cartilage is the most flexible? A) Hyaline cartilage B) Elastic cartilage C) Fibrocartilage 2) Which one of the following cells is responsible synthesis of protein and fibers of the matrix of the cartilage? A) Chondroblasts. B) Chondrocytes. C) Fibroblasts. D) Osteocytes. 3) Which one of the following cartilage types has elastic fibers in its matrix? A) Hyaline cartilage. B) Elastic cartilage. C) Fibrocartilage. Q2. Match each type of cartilage with its correct site in the human body. Cartilage type Site 1) Hyaline cartilage A) Intervertebral disc 2) Elastic cartilage B) Costal cartilage 3) Fibrocartilage C) Ear pinna 1)……….. 2)………… 3)………………….. 6