CLASSIFICATION OF CONNECTIVE TISSUE The connective tissues are classified into various types depending on the following Four Factors. 1. Relative proportion of the various fibers present 2. Compactness and arrangement of fibers 3. Nature of ground substance (matrix) 4. Types of cells On these ground the connective tissues are divided into basic Groups A. Embryonal Connective Tissue B. Adult Connective Tissues Connective Tissue Adult Embryonal Proper Cartilage Bone Mucous Mesenchyme Hyaline Fibro Dense Loose Areolar Elastic Regularly Arranged Irregularly Arranged Reticular Adipose Embryonal Connective Tissue Mesenchyme: developmentally, the connective tissue are derived from mesoderm (Mesenchyme) which one of the three Primary embryonic Layers (others two are ectoderm and Endoderm). Immature connective tissue of embryo derived from the mesoderm is called as Mesenchyme. Embryonic Connective Tissue --- Mesenchyme • Consists of cells and ground substance with reticular fibers • Gives rise to all types of Connective Tissues Embryonal Connective Tissue Mucous Tissue: At the later stages of development of foetus the mesnechmye acquired abundant of fibers, the increased number of fibers in mesenchyme now called as Mucous, which widely distributed through out the body of embryo. Mucous Tissue 1-LOOSE CONNECTIVE TISSUE Loose Areolar connective Tissue: This type is widely distributed through out the body. All three basic components of connective tissue (cells, fibers and ground substance) are best represented in the loose aerolar connective tissue. Green Lines - Collagen Fiber Blue Circle - Mast Cells Yellow arrows - Elastic Fiber 1- Loose Areolar connective Tissue: The two most common cell types, fibroblast and histiocytes are present but other varieties of cells also present. Collagenous fibers are more abundant but elastic fibers are also present. Reticular fiber are few in number. Distributions: Subcutaneous Tissue (Superficial & deep fascias) Green Lines - Collagen Fiber Mesentery Blue Circle - Mast Cells Omentum Yellow arrows - Elastic Fiber Connective tissue specialised Adipose: • Location – deep to skin: sides, buttocks, breasts; padding around eyeballs and kidneys • Function – insulation, mechanical support, stores energy. Reticular: • Location – spleen, lymph nodes, bone marrow • Function – supporting framework for haemopoietic organs •Mucoid: umbilical cord, incompressible 2- RETICULAR CONNECTIVE TISSUE This variety of loose connective tissue consists of reticular cells and reticular fibers. Reticular cells have a stellate shape and possess long processes which pass indifferent directions to make contact with neighbouring cells. Reticular Tissue 2- RETICULAR CONNECTIVE TISSUE Distributions: Forms the supporting network of the liver, spleen, bone marrow and lymphoid organs. Functions: Precursor for Fibroblast Producing Reticular fibers Phagocytic Properties 3- ADIPOSE TISSUE This variety of loose connective consists of entirely of fat cells, organized into lobules which are separated from each other by fibrous septa. Within a lobule, the individual fat cells are supported by a mesh work of delicate reticular fibers. 3- ADIPOSE TISSUE Distributions: Functions: Food reserve for the body Chief site for energy storage Mechanical functions for shock absorbing pad for e.g. sole of foot. Temperature Regulation By production heat as a result of metabolism of fat. By acting as the insulator under the skin & preventing the heat loss. Types of Adipose Tissue Two types of adipose tissue are found in animals: white adipose tissue and brown adipose tissue. Brown Adipose CT White Adipose CT Brown Adipose Connective Tissue Brown adipose tissue is present in significant amounts in human infants. Its distributions is very limited in the adult In adult it is found in the mediastinum, the subcutaneous tissue between the scapula, the area around the kidney and the area along the aorta. Brown Adipose Connective Tissue Brown adipocytes are small cells that contain a centrally-placed nucleus and large numbers of mitochondria. Brown adipocytes are multilocular cells, i.e., each cell contains multiple small lipid droplets. Brown Adipose Connective Tissue Brown adipose tissue has a high metabolic rate capable of generating relatively high amounts of heat, a process that is physiologically important to infants prior to the maturation of their thermoregulatory mechanisms. White Adipose Connective Tissue White adipose tissue is the principal type of adipose tissue of the adult human. The tissue, which is scattered about the body, occupying positions in skin and around and within a variety of other organs White Adipose Connective Tissue Distributions It is the largest storage reservoir of metabolic fuel in the body, it serves as a thermal insulator, in the case of the skin, and a protective cushion, in the case of the adipose that surrounds organs. Its size and distribution vary according to a variety of factors, including age and sex. White Adipose Connective Tissue Its important histologic characteristics are: The adipocytes are relatively large, compared to brown adipocytes, and are dominated by the lipid droplet. White adipocytes are unilocular cells, i.e., each cell contains a single large lipid droplet, a cytoplasmic inclusion that contains triacylglycerols and fatsoluble substances. White Adipose Connective Tissue The large lipid droplet appears empty because the lipid is lost during routine histological preparation, and it displaces the rest of the cell toward the cells' periphery, flattening the nucleus along the edge of the cell, giving the cell a signet ring appearance. The tissue is well vascularized, with microvascular vessels found in the sliver of loose connective tissue found between adjacent cells. DENSE CONNECTIVE TISSUE According to the arrangement of its component fibers, the dense connective tissue is subclassify into two categories: 1. Regularly Arranged connective Tissue 2. Irregularly Arranged connective Tissue REGULARLY ARRANGED CONNECTIVE TISSUE They are three types:a- Tendons: composed of almost entirely of closely packed collagen fibers. A few fibroblasts are present b- Aponeuroses: have same structure as the tendon, but they are broad and thin. c- Ligaments: same as tendons but more sronger. IRREGULARLY ARRANGED CONNECTIVE TISSUE This type of dense connective tissue occurs in the form of sheets. It mainly consists of collagenous fibers, but elastic and reticular fibers are also present Distributions: Dermis of skin Capsules of some organs (liver, spleen, lymph nodes Fibrous Sheaths of cartilage (Perichondrium) Fibrous Sheaths of bone (periosteum) Uploaded By………