Dense regular connective tissue.

(a): Micrograph shows a longitudinal section of dense regular connective tissue of a tendon. Long, parallel bundles of collagen fibers fill the spaces between the elongated nuclei of fibrocytes. X100. H&E stain. (b): The electron micrograph shows one fibrocyte in a cross-section of tendon, revealing that the sparse cytoplasm of the fibrocytes is divided into numerous thin cytoplasmic processes extending among adjacent collagen fibers. X25,000.

SKELETAL CONNECTIVE TISSUE:
CARTILAGE:
- Hyaline cartilage	It represents transparent cartilage, the homogenous intercellular substance of which contains many collagenous fibres. In the zone of the young cartilage (just under the perichondrium) chondrocyters are flattened and are present singly. Towards the centre of a mass of hyaline cartilage the chondrocytes are large and are usually present in groups (isogenous groups).
- Elastic cartilage	It is similar in many ways to hyaline cartilage. The main difference is that the intercellular substance contains both collagen and elastic fibres. It is less transparent than hyaline cartilage.
- Fibrocartilage	It is not transparent. The cells are arranged in short rows.
BONE
- Woven bone	It is newly formed bone which does not have a lamellar structure. The collagen fibres are present in bundles that appear to run randomly in different directions, interlacing with each other
- Cancellous bone	Cancellous bone is made up of bony trabeculae that form the meshwork. The trabeculae enclose wide spaces which are filled in by bone marrow. They receive nutrition from blood vessels in the bone marrow.
- Compact bone
1. external circumferential lamellae	They form the external wall of the compact bone (beneath the connective tissue periosteum).
2. osteogenic layer
a. osteon	It consists of Haversian canal surrounded by the lamellae arranged in the form of concentric rings.
b. interstitial lamellae	These lamellae are remnants of osteons the greater parts of which have been destroyed.
3. internal circumferential lamellae	They form the internal wall of the compact bone (along the marrow cavity).
DENTIN OF TOOTH
CEMENT OF TOOTH

STRUCTURE OF CARTILAGE:

- CELLS

- INTERCELLULAR SUBSTANCE (MATRIX)

CELLS:
Chondrocytes	They lie in spaces (or lacunae).
INTERCELLULAR SUBSTANCE:
Ground substance	It is made up of complex molecules containing proteins and carbohydrates (proteoglycans).
Collagen fibres	They are made up of Type II collagen.

HYALINE CARTILAGE AND PERICHONDRIUM

It represents transparent cartilage, the homogenous intercellular substance of which contains many collagenous fibres. In the zone of the young cartilage (just under the perichondrium) chondrocyters are flattened and are present singly. Towards the centre of a mass of hyaline cartilage the chondrocytes are large and are usually present in groups (isogenous groups).

Дата добавления: 2015-10-30