• They are supporting tissue, forms endoskeleton of vertebrates, protect vital organs
• types-

1. Cartilage: Hyline cartilage, elastic cartilage and fibrous cartilage
2. Bone: spongy bone and compact bone

1. Cartilage:

• It is tough, hard but a flexible connective tissue. It can resist strain and can absorb mechanical shock.
• It consists of solid or semisolid matrix in which cartilage cell (chondrocytes) and fibres are embedded.

Structure:

• cartilage is enclosed in a sheath of white fibrous connective tissue called Below the perichondrium, there is layer chondroblast cell, which form chondrocytes.
• Chondrocytes are dispersed in the matrix and occur in the fluid filled space called lacunae.
• Each lacunae contain 2-4 chondrocytes. Each chondrocytes is a large, angular cell with distinct nucleus.
• The matrix lacks the blood vessels.

types:

• Depending upon matrix, cartilage are of 3 types

i. Hyaline cartilage:

• The matrix is glass like semi transparent, homogenous and has fine collagen fibres
• It is slightly elastic and compressible.
• Found in- nose, larynx, trachea, ends of bone. It forms skeleton of cartilage fish

ii. Elastic cartilage:

• The matrix is semi opaque and has network of yellow elastic fibres
• It is highly elastic and flexible. The tissue recover the shape quickly
• Found in-external ear, epiglottis, and pharynx (Eustachian tube)

iii. Fibrous cartilage:

• The matrix has bundles of densely packed white collagen fibres
• It provides great strength and little degree of flexibility
• It acts as a shock absorber by giving a cushioning effect
• Found in- intervertebral discs and at pubis symphysis

2. Bone:

• It is supportive and protective tissue.
• The matrix is solid and calcified. (70% salts of calcium and phosphate: hydroxyapatite-Ca10(PO4)6(OH)2, 30 %fibrous protein; Ossein).
• Bone cell (Osteocyte) and collagen fibre are embedded in solid matrix

Structure:

• Each bone is enclosed in a layer of white fibrous connective tissue, called periosteum.
• Matrix is arranged in concentric circles called lamellae.
• Number of osteoblast cell and osteocytes are arranged in between the lamellae, in the fluid filed space called Lacunae.
• Each lacunae has fine cytoplasmic processes called canaliculi, which connect with other lacunae.
• Osteoblast are active bone cell, while osteocytes are inactive osteroblats

types:

i. Compact bone:

• Compact bone is arranged in concentric ring structures called osteons (Haversian canal system) in the center of each ring is a structure called a Haversian canal. This canal carries blood vessels through
  the bone to nourish the cells embedded within the tissue.
• Around the Haversian canal, rings of bone tissue are found called lamellae. Within these rings, are space called lacunae that contain osteocytes
• Radiating out from the lacunae are tiny channels that allow interaction of the cells with the blood supply,exchanges of nutrients, gases, called canaliculi.
• Canal of Volkman connects various Haversian canal systems together
• In the centre of compact bone, bone marrow cavity is present, filled with yellow bone marrow

ii. Spongy bone:

• The matrix is web like rather than solid with number of space in between.
• Also known as trabeculae
• Found in epiphysis of long bone
• It lacks Haversian canal system and Volkman canal
• It contains red bone marrow, which forms RBC and WBC.

Supportive connective tissue: Cartilage and Bone

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