Cartilage

The cartilage is a non-vascular fibrous connective tissue responsible for acting as a model for the later development and growth of the skeletal bones in our body. The cartilage is usually composed of a very dense network of fibres called collagen, which is usually embedded in a very dense and gelatinous ground or matrix substance that has the consistency and thickness of plastic. These form the skeleton of mammal embryos before bone formation and development occur and even persist in some parts of the human body after the growth and development are complete. 

Cartilage Key Points 

A short and brief structure of all key points of cartilage are given below.

1. The cartilage is a flexible and soft connective as well as fibrous tissue that is structurally and functionally very different from the bones. 
2. The cartilage is avascular.
3. The microarchitecture of the cartilage is less and differently organised than that of the bone. 
4. The nerves of the body do not pass through the cartilage. This is why any injury to the cartilage heals slower than other body parts, as it completely relies on the inter-diffusion of nutrients. 
5. The main cells that are found in the cartilage are chondrocytes. 
6. The ground substance of the cartilage is known as Chondroitin Sulphate. It is a gelatinous and dense ground matrix-like substance in which the Chondrocytes are embedded. 
7. The fibrous sheath of the cartilage is known as Perichondrium. 

Structure of Cartilage 

The cartilage is a dense, firm gel-like substance with fibrous connective tissue. It is mostly made up of elastin and collagen fibres. The ground matrix-like substance found in the cartilage is called Chondroitin Sulphate. They are polysaccharide derivatives that make a complex called proteoglycan on combining with protein molecules. The proteoglycan-based matrix or ground substance is formed by the cartilage cells known as Chondroblasts. These chondroblasts from chondrocytes are found in small chambers in the ground matrix, called lacuna. 

The cartilages are distinctly separated from the surrounding or nearby body tissues by a fibrous sheath known as Perichondrium. The perichondrium again consists of two separate layers:

1. The first layer is the Outer Fibrous Layer, which is responsible for providing protection mechanical support to the body parts as well as helps in attachment of other body structures, 
2. The second layer is the Inner Cellular, which is very important and responsible for the growth, development, and maintenance of the present cartilages.

Types of Cartilage

The cartilage found in our bodies is mainly of three distinct types. They have slightly different structures and functions than each other as well as the bones.

1. Hyaline Cartilage is the most common kind of cartilage found in almost every part of the body. The hyaline cartilage is very smooth and contains a matrix made up of tightly-packed fibres of collagen, which makes it look tough and rigid and a little more flexible than bones. The bluish-white tinted ground matric of the hyaline cartilage is elastic. Also, it consists of Chondroitin Sulphate in the ground matrix along with other chondrocyte cells and fine fibrils of collagen. The hyaline cartilage joints include the connection that joins the ribs with the sternum, nasal, and articular cartilage – which is found covering the bone surfaces in many joints. 
2. Fibrocartilage – This cartilage is said to be the toughest and hardest among all the three cartilage types. Its structure does not show the presence of the fibrous sheath (perichondrium). The matrix of this cartilage is packed densely with various bundles of collagen fibres. They are most embedded with chondrocytes, making this cartilage very durable and tough. This feature of this cartilage makes it an appropriate tissue to provide support to body attachments and provide rigidity. The fibrocartilage joints examples include the intervertebral discs, the callus, Menisci, cartilage found between the pubic symphysis, and the junction where the tendons of the body enter into bones. 
3. Elastic Cartilage – The third and final type of cartilage is known for providing support to various attachments in our body. This cartilage, yellowish in colour, is surrounded by a fibrous sheath, the perichondrium. The cartilage cells, chondrocytes, are present between a connection of threadlike elastic fibres. This cartilage is very flexible and resilient due to the abundant presence of elastic fibres. This type of cartilage is usually found in the auricle of the outer ear. 

Conclusion 

Cartilage is a very important component of the human body. It forms the mammalian embryo structure’s basic framework until the body doesn’t develop and grow the bones themselves. The cartilage relies on nutrient diffusion to receive all essential substances; hence it always has an unfortunate delay in its recovery from any injury. It is responsible for giving support and rigidity to various joints and other attachments of our body.