CONNECTIVE TISSUE
LOSS CONNECTIVE TISSUE :
1.ADIPOSE :
Adipose characterized by presence of considerable amount of fat in cytoplasm and so called FAT CELLS
Two types of Adipose tissue,
- White Adipose
- Brown Adipose
The color of this type of adipose tissue varies from white to light yellow. Histologically the white adipose tissue characterized by the presence of adipocytes which only a single fat droplet and are called unilocular adipocytes.
These cells have a large size and measure 50-150 um in diameter.
Isolated adipocytes have a spherical shape but appear polyhedral in the adipose tissue because of close of cells. Most of the space within an adipocyte is occupied by the large fat droplet. The nucleus of the adipocyte is also displaced to one side of the lipid droplet and is almost flat in shape In routine H&E stained tissue sections the fat is dissolved out and the space previously occupied by the fat droplet appears as a colorless rounded or oval area. Consequently, the cytoplasm and the nucleus of the unilocular adipocyte are seen as a rim around the central empty space. The cosinophilic cytoplasm and the basophilic nucleus of the cell together exhibit a typical signet-ring appearance.
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| Unilocular Adipose |
Found In.
Adults
BROWN ADIPOSE :
The brown adipose tissue consists of multilocular adipocytes, which store fat in their cytoplasm as multiple small fat droplets. Upon naked eye examination, this tissue from tan to reddish brown in color because of ranges two factors:
(1)The brown adipose tissue contains a large number of blood capillaries
(2)The brown adipose tissue possess exceptionally abundant mitochondria, which contain the colored enzymes cytochromes.
The adipocytes of brown adipose tissue appear polygonal in sections and have a considerably smaller diameter than that of the adipocytes of white adipose tissue. The cytoplasm is also relatively abundant and contains numerous fat droplets of various sizes.
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| Multilocular Adipose |
The nucleus is spherical in shape.
Numerous mitochondria
small Golgi apparatus
small amounts of SER and RER are also present.
Connective tissue septa divide the brown adipose tissue into well-defined lobules.
Brown adipose tissue is very abundant in hibernating animals. In humans, a large amount of brown adipose tissue is found in the new born, As the body grows, the amount of this tissue gradually decreases and become greatly reduced after the first decade of life. In the body of an adult human being, the brown adipose tissue is found to be located in the posterior triangle of neck and in the mediastinum. It is also found around the abdominal aorta and kidneys. The principal function of the brown adipose tissue is production of body heat. The adipocytes of brown adipose tissue produce heat by non-shivering thermogenesis.The heat produced by the brown adipose tissue is used to warm the blood upon arousal from hibernation. In humans, the brown adipose tissue plays a vital role in the maintenance of normal body temperature in the new born and in young children. Physiological role of the brown adipose tissue in the adult humans is not well-understood.
Found In.
Rich of blood capillaries. Rich of mitochondria.
Because there is heat production abundant in Fetus and Children.
2. RECTICULAR CONNECTIVE TISSUE :
This variety of connective tissue proper consists of reticular fibers and reticular cells. The reticular fibers are made up collagen type III and are arranged in the form of a mesh- like network.
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| (Reticular connective tissue in the red pulp of spleen) |
The reticular cells are considered to be a special variety of fibroblasts. These cells have a stellate shape and possess long processes which pass in different directions to make contact with those of the neighboring cells. Most of the protoplasmic processes of the reticular cells are wrapped around or extend along the reticular fibers. This specific arrangement creates a special trabecular system that forms the architectural framework of hemopoietic and lymphoid organs (bone marrow, spleen and lymph nodes). The spaces within the trabecular meshwork are occupied by scanty ground substance and cells, which are lymphocytes in the lymphoid organs, and precursors of blood cells in the bone marrow.
Found In.
Organs Liver
Sapleen
Lymph Node
Bone marrow
3. AREOLAR
Superficial Fascia - D- fasciae
Omentum
Messentery
DENSE CONNECTIVE TISSUE :
This variety of connective tissue proper is characterized by close packing of its fibers. It contains fewer cells and much smaller amount of the ground substance as compared to the loose connective tissue. The dense connective tissue is less flexible but it is far more resistant to stress. According to the arrangement of its component fibers the dense connective tissue has two types.
1.DENSE IRREGULAR CONNECTIVE TISSUE:
This variety of dense connective tissue usually occurs in the form of sheets. It consists mainly of bundles of collagen fibers which are interwoven into a meshwork. Such a meshwork resists stress from all directions. In addition to collagen fibers, the dense irregular connective tissue also contains fine networks of clastic fibers scattered among the collagen bundles. Examples of the dense irregular connective tissue are deep fascia and capsules of organs like the thyroid gland, prostate gland, liver, kidneys, and testes, etc. The perichondrium of the cartilage and periosteum of the bone also consist of dense irregular connective tissue.
Found In:
Dermis of skin
Capsule of liver
Saleen
Lymph Node
Prichondrium
Periosteum
2.DENSE REGULAR CONNECTIVE TISSUE:
In this variety of dense connective tissue, the fibers are densely packed and are arranged parallel to each other. Dense packing of component fibers provides maximum strength to this tissue.
Found In:
Tendons
Ligaments
Aponeurosis
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