Cartilage

Cartilage is a type of connective tissue Connective tissue Connective tissues originate from embryonic mesenchyme and are present throughout the body except inside the brain and spinal cord. The main function of connective tissues is to provide structural support to organs. Connective tissues consist of cells and an extracellular matrix. Connective Tissue derived from embryonic mesenchyme that is responsible for structural support, resilience, and the smoothness of physical actions. Perichondrium ( connective tissue Connective tissue Connective tissues originate from embryonic mesenchyme and are present throughout the body except inside the brain and spinal cord. The main function of connective tissues is to provide structural support to organs. Connective tissues consist of cells and an extracellular matrix. Connective Tissue membrane surrounding cartilage) compensates for the absence of vasculature in cartilage by providing nutrition and support. The abundant ground substance contains large amounts of chondroitin sulfate, hyaluronic acid, and water (80% of cartilage is water). All types of cartilage contain type II collagen produced by chondrocytes. Elastic cartilage additionally contains elastic fibers, whereas fibrocartilage also contains dense connective tissue Connective tissue Connective tissues originate from embryonic mesenchyme and are present throughout the body except inside the brain and spinal cord. The main function of connective tissues is to provide structural support to organs. Connective tissues consist of cells and an extracellular matrix. Connective Tissue (type 1 collagen).

Last update:

Editorial responsibility: Stanley Oiseth, Lindsay Jones, Evelin Maza

Table of Contents

Share this concept:

Share on facebook
Share on twitter
Share on linkedin
Share on reddit
Share on email
Share on whatsapp

Overview

Definition

Cartilage is a type of connective tissue Connective tissue Connective tissues originate from embryonic mesenchyme and are present throughout the body except inside the brain and spinal cord. The main function of connective tissues is to provide structural support to organs. Connective tissues consist of cells and an extracellular matrix. Connective Tissue that forms structural components of the human skeleton and provides support to various organs.

Composition

Chondrocytes:

  • The major cell type of the cartilage tissue
  • Synthesize extracellular matrix (ECM) components and become embedded in them (lacunae)
  • Young chondrocytes retain the ability to divide; daughter cells secrete new ECM and become surrounded by the new lacunae.
  • Have low oxygen needs; nutrition is provided by perichondrium since cartilage is lacking blood vessels and innervation
  • Stimulated by somatotropins from the pituitary, inducing synthesis of sulfated glycosaminoglycans (GAGs) and secretion of proteoglycans

Chondroblasts:

  • Perichondrial cells that are located at the periphery of the cartilage and develop into chondrocytes 
  • Conversion of chondroblasts to chondrocytes occurs when chondroblasts become surrounded by the new matrix they produce.

Extracellular matrix:

  • Produced by chondrocytes 
  • Abundant, usually of firm consistency and resistant to compression
  • Composed of collagen (type Ⅱ most prevalent), proteoglycans, and glycoproteins
  • Chondroitin sulfate (aggrecan) is the most abundant proteoglycan in the matrix of hyaline cartilage

Related videos

Chondrogenesis

Embryonic development

  • Cartilage develops from embryonic mesenchyme.
  • Rounding up mesenchymal osteoprogenitor cells indicates the beginning of the process.
  • Chondroblasts are formed and begin secreting ECM consisting mostly of aggrecan and type Ⅱ collagen.
  • Chondroblasts are converted to chondrocytes.
  • Both cells are rich with rough endoplasmic reticulum (RER) for collagen synthesis.
  • Cartilage growth:
    • Interstitial growth: mitotic division of pre-existing chondrocytes → ECM formation
    • Appositional growth: formation of chondroblasts from progenitor cells in the perichondrium
    • Isogenous cells are formed by the mitotic division of chondroblasts.

Skeletal growth during childhood

  • Embryonic skeleton is composed primarily of cartilage.
  • Cartilage gradually calcifies and is replaced by bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Structure of Bones as chondrocytes are replaced by osteocytes.
  • Epiphyseal plate is a thin layer of cartilage that persists at the ends of long bones after birth and allows for longitudinal bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Structure of Bones growth.
  • Once the epiphyseal plate is completely ossified, no further longitudinal growth occurs.

Regeneration and repair

  • Since perichondrium loses the ability to form new cells, the regeneration of cartilage is almost nonexistent.
  • Perichondrial cells will produce mostly dense connective tissue Connective tissue Connective tissues originate from embryonic mesenchyme and are present throughout the body except inside the brain and spinal cord. The main function of connective tissues is to provide structural support to organs. Connective tissues consist of cells and an extracellular matrix. Connective Tissue.
  • Repair is also limited since chondrocytes are locked up in lacunae and cannot travel to damaged areas.

Types of Cartilage

There are 3 main types of cartilage tissue:

  • Hyaline cartilage (most abundant)
  • Elastic cartilage
  • Fibrocartilage
Table: Characteristics of 3 types of cartilage
Hyaline cartilage Elastic (yellow) cartilage Fibrocartilage
Composition of extracellular matrix
  • Type II collagen (randomly oriented fibrils)
  • Aggrecan
  • Type II collagen
  • Aggrecan
  • Elastic fibers (yellow)
  • Type II collagen (parallel fibrils)
  • Type I collagen
Major cells
  • Chondrocytes
  • Chondroblasts
  • Chondrocytes
  • Chondroblasts
  • Chondrocytes
  • Fibroblasts
Arrangement of chondrocytes Isolated or in small isogenous groups Usually in small isogenous groups Isolated or in isogenous groups arranged axially
Presence of perichondrium Yes (except at epiphysis Epiphysis The head of a long bone that is separated from the shaft by the epiphyseal plate until bone growth stops. At that time, the plate disappears and the head and shaft are united. Structure of Bones and articular cartilage) Yes No
Locations
  • Upper respiratory tract
  • Articular ends and epiphyseal plates of long bones
  • Fetal skeleton
  • External ear
  • External acoustic meatus
  • Auditory tube
  • Epigottis and larynx Larynx The larynx, also commonly called the voice box, is a cylindrical space located in the neck at the level of the C3-C6 vertebrae. The major structures forming the framework of the larynx are the thyroid cartilage, cricoid cartilage, and epiglottis. The larynx serves to produce sound (phonation), conducts air to the trachea, and prevents large molecules from reaching the lungs. Larynx
  • Intervertebral discs
  • Pubic symphysis
  • Meniscus and certain other joints
  • Insertions of tendons
Functions
  • Provides smooth, low-friction surfaces in joints
  • Structural support for respiratory tract
  • Provides flexible shape
  • Support of soft tissues
  • Provides cushioning
  • Tensile strength
  • Resistance to tearing and compression

Clinical Relevance

  • Osteoarthritis Osteoarthritis Osteoarthritis (OA) is the most common form of arthritis, and is due to cartilage destruction and changes of the subchondral bone. The risk of developing this disorder increases with age, obesity, and repetitive joint use or trauma. Patients develop gradual joint pain, stiffness lasting < 30 minutes, and decreased range of motion. Osteoarthritis: a disease caused by degeneration of articular (hyaline) cartilage. The process of degradation and faulty repair is mediated by chondrocytes. Risk factors are age, obesity Obesity Obesity is a condition associated with excess body weight, specifically with the deposition of excessive adipose tissue. Obesity is considered a global epidemic. Major influences come from the western diet and sedentary lifestyles, but the exact mechanisms likely include a mixture of genetic and environmental factors. Obesity, female gender, and joint trauma. 
  • Osteochondritis dissecans Osteochondritis dissecans Osteochondritis dissecans (OCD) is an orthopedic disorder characterized by the detachment of a focal segment of subchondral bone and cartilage as a result of focal aseptic necrosis. This can occur at any age, but it is most commonly seen in adolescents who participate in competitive sports. Osteochondritis Dissecans: a joint disorder characterized by focal aseptic necrosis of the articular cartilage and subchondral bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Structure of Bones. This condition is usually associated with the detachment of a bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Structure of Bones-cartilage fragment, which becomes displaced in the joint space. Causes pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain and swelling of the affected joint, which catches and locks during movement. 
  • Chondrosarcoma Chondrosarcoma Chondrosarcoma is a malignant bone tumor characterized by the production of a cartilaginous matrix. This bone tumor most commonly affects adults over the age of 50. Chondrosarcoma usually presents with a slowly increasing mass (or swelling) with a dull achy pain. Chondrosarcoma: malignant bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Structure of Bones tumor of chondrocytes that most commonly affects pelvic and long bones. Most common in older adults. Usually presents as a slow-growing mass associated with dull achy pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain. Diagnosed with imaging and biopsy, and treatment involves wide surgical excision.
  • Enchondroma: a benign bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Structure of Bones tumor originating in cartilage. This condition rarely causes pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain or other symptoms, and is most commonly picked up incidentally on imaging. Usually small in size (< 5 cm) and does not require treatment.

References

  1. Fawcett D.W. Cartilage. Retrieved 30 May 2021, from https://www.britannica.com/science/connective-tissue/Cartilage#ref470898
  2. Fawcett D.W. (1994). A Textbook of Histology, 12th ed., chapter 5, pp. 133–169.

USMLE™ is a joint program of the Federation of State Medical Boards (FSMB®) and National Board of Medical Examiners (NBME®). MCAT is a registered trademark of the Association of American Medical Colleges (AAMC). NCLEX®, NCLEX-RN®, and NCLEX-PN® are registered trademarks of the National Council of State Boards of Nursing, Inc (NCSBN®). None of the trademark holders are endorsed by nor affiliated with Lecturio.

Study on the Go

Lecturio Medical complements your studies with evidence-based learning strategies, video lectures, quiz questions, and more – all combined in one easy-to-use resource.

Learn even more with Lecturio:

Complement your med school studies with Lecturio’s all-in-one study companion, delivered with evidence-based learning strategies.

User Reviews

0.0

()

¡Hola!

Esta página está disponible en Español.

🍪 Lecturio is using cookies to improve your user experience. By continuing use of our service you agree upon our Data Privacy Statement.

Details