Cartilage Histology PDF

# Cartilage ## Prepared by Dr. Ahmed A. Morsi Assist. Prof. of Histology & Cell Biology ## Learning objectives: - By the end of this lecture, you will be able to: - Define cartilage. - Classify cartilage. - Mention the location of cartilage in the human body. - Know the microstr...

# Cartilage ## Prepared by Dr. Ahmed A. Morsi Assist. Prof. of Histology & Cell Biology ## Learning objectives: - By the end of this lecture, you will be able to: - Define cartilage. - Classify cartilage. - Mention the location of cartilage in the human body. - Know the microstructure of cartilage. ## Cartilage: ### Definition: It is an avascular (no BVs) specialized type of CT in which the matrix is firm or rubber, so having resilient nature. ### Function: 1. Support 2. Keep patent air way 3. Provide smooth sliding surface for joint 4. Shock absorber ## Structure of Cartilage Like any type of CT, the cartilage is composed of cells, fibers and ground substance: ### a) Cartilage cells: 1. Chondrogenic cell (mother cell for all types of cartilage cells). 2. Chondroblast (immature cartilage cell) - Located on the surface of cartilage & perichondrium. It secretes the cartilage matrix and cartilage fibers. 3. Chondrocyte (mature cartilage cell) - Mature cell that secrete enough matrix which sink and completely surrounded by it and imprisoned in lacunae. They are present in isogenous groups of 2, 4, 8 cells (cell nest) ### b) Cartilage fibers: Collagen and elastic fibers according to the type of cartilage. ### c) Ground substance (matrix): 1. Rubbery, markedly basophilic. 2. Composed of GAGs, glycoprotiens and water ## Types of Cartilage According to the type of fibers embedded in the matrix, cartilage is classified into 3 types: | Type | Fiber | | :-------------------------------- | :----------------- | | I. Hyaline cartilage | Collagen fiber II | | II. Yellow elastic cartilage | Elastic fibers | | III. White fibrocartilage | Collagen fiber I | ### I) Hyaline cartilage: - Site: - Fetal skeleton - Epiphyseal plate - Costal cartilage - Articular surfaces - Respiratory passages e.g nose, trachea ### Structure: 1. Perichondrium: irregular white fibrous CT surround cartilage. No perichondrium in articular cartilage 2. Cartilage cells 3. Fibers: collagen II 4. Matrix: huge amount, basophilic, produced by chondroblast ### II) Yellow elastic cartilage - Sites: - Ear pinna - Eustachian tube - Epiglottis - External auditory canal ### Structure: 1. Perichondrium 2. Cartilage cells 3. Fibers: elastic fiber forming network within the matrix 4. Matrix: less than in hyaline type ### III) White fibrocartilage: - Sites: - Intervertibral disc - Symphysis pubis - Mandibular joint - Sternoclavicular joint - Acetabulum ### Structure: 1. No perichondrium 2. Fibers: collagen fiber I present in thick parallel bundles 3. Cartilage cells: present in rows between the collagen bundles 4. Matrix: very scanty ## Reference: - Junqueira's Basic Histology: Text and atlas, 13th Edition, 2013. Anthony L. Mescher Thank You