It is a type of connective tissue in which the matrix is hard and rigid due to the presence of inorganic salts. The matrix encloses few cells. Fibres may be present or absent. It is also known as skeletal tissue since it forms the internal supporting framework (endoskeleton) of the body.
Types of supporting tissue
Based on the components of matrix, supporting tissue can be classified into
1. Cartilage
2. BoneCartilage
t is a type of supporting tissue in which the matrix is characterized by more of organic substances (nearly 85%). The rigid, homogenous matrix is known as chondrin. It lies enclosed in a fibrous connective tissue covering called perichondrium. Chondrin encloses numerous spherical or oval spaces called lacunae. Each lacuna contains either 1 or 2 or 4 cartilage cells or chondriocytes. These cells are capable of limited mitotic divisions. Fibres may be present or absent.
Based on the composition of matrix, cartilage can be distinguished into the following types:
- Hyaline cartilage: is the simplest and the most common type of cartilage. It has a rigid, homogenous matrix called chondrin enclosed in a fibrous membrane called perichondrium. Fibres are absent. The matrix contains numerous spherical or oval spaces called lacunae, which encloses either 1 or 2 or 4 chondriocytes.
Hyaline cartilage is found forming the entire endoskeleton in the embryonic stage. In adults, it occurs in the wall of the larynx and trachea.
fig. 5.66 Hyaline Cartilage
- Fibrous cartilage is a modification of hyaline cartilage in which the matrix contains white fibers. Hence, the cartilage attains more of rigidity.
It is found forming intervertebral discs between the vertebrae. It also occurs at the joints between bones.
- Elastic cartilage is a modification of hyaline cartilage in which the matrix has yellow fibres. Hence, the cartilage attains elasticity.
Elastic cartilage forms a flap called epiglottis in the throat. It is also present in the pinna or external ear.
- Ossified or calcified cartilage is a modification of hyaline cartilage in which the matrix is deposited with calcium salts particularly, calcium phosphate. Hence, the cartilage attains hardness almost equivalent to that of a bone. Ossified cartilage occurs in the nose tip and at some bone joints like pubic symphysis.