Connective Tissue PDF

Connective Tissue Ema Bexheti Defining Connective Tissue Connective tissue are a group of tissues that share several common developmental and structural properties. The term Supporting/ connective tissue is applied to tissues that provide general structure, mechanical strength, sp...

Connective Tissue Ema Bexheti Defining Connective Tissue Connective tissue are a group of tissues that share several common developmental and structural properties. The term Supporting/ connective tissue is applied to tissues that provide general structure, mechanical strength, space filling, physical and metabolic support for more specialized cells. The connective tissue develops from mesenchyme cells, (embryonic type of tissue. the embryonic connective tissue is present in the umbilical cord and in the pulp of the developing teeth.  Mesenchyme cells give rise to other connective tissues such as cartilage, bone and blood. The connective tissue consists of cells and extracellular material called the matrix.  Matrix consist of connective tissue fluid, the ground substance within which are embedded the different protein fibers (collagen, reticular, and elastic.) Connective tissue binds, anchors and supports various cells, tissue and organs of the body. Provides gel-like medium of the ground substance for exchange of nutrients, oxygen and metabolic waste. Connective matrix contains numerous types of cells that provide protection and defense. Structural properties Tensile Strength- to resist pulling, stretching and tearing. Elasticity- facilitate the return to the original shape after mechanical distortion. Volume provided by glycoproteins and complex carbohydrates with profound water binding ability that forms a wet gel known as ground substance. Classification of connective Tissue Loose Connective Tissue Dense Connective Tissue It is widespread Contains thicker and more densely Loose, irregular packed collagen fibers, with fewer cells types and less ground substance. arrangement of connective Collagen fibers exhibit a random tissue fibers and abundant irregular orientation. ground substance. Present in the dermis of skin, capsules of Collagen fibers, fibroblasts, different organs and in areas in need of adipose cells, mast cells, strong binding and support. plasma cells, and Contrast dense regular connective tissue macrophages predominate contains densely packed collagen fibers in the loose connective that exhibit a regular and parallel tissue. arrangement. ( found in tendons and ligaments) Cells of the Connective Tissue Fibroblast Fibrocyte Adipose (fat) cells white adipose tissue brown adipose tissue Macrophages or histiocytes Mast cells Plasma cells Leukocyte Types of Collagen fibers They are thick, fibrous proteins that do not branch. Type I: found in dermis of the skin, tendons, ligaments, fasciae, fibrocartilage, the capsule of the organs and bones.  Type II: hyaline cartilage, elastic cartilage, vitreous body of the eye.  Type III: Delicate supporting meshwork in such organs as the lymph nodes, spleen, and bone marrow.  Type IV: present as meshwork in the basal lamina of the basement membrane, to which the basal regions of the cells attach with the hemisdesmosomes. Reticular Fibers Consist of mainly type III collagen, are thin and form a delicate netlike support framework in the liver, lymph nodes, spleen, hemopoietic organs and other locations where blood and lymph are filtered. They support capillaries, nerves and muscle cells. Elastic Fibers Are thin, small branching fibers that are capable of stretching and returning to their original state( recoil). Less tensile strength than collagen fibers and are composed of microfibrils and protein elastin. Found in abundance in the lungs, bladder wall, and skin. In the walls of aorta and pulmonary trunk. – this allows for stretching and recoiling of these vessels during powerful blood ejections from heart ventricles. Types of cells Connective Tissue, Capillary, and Mast Cell in Mesentery of Small Intestine This micrograph illustrates the connective tissue from the mesentery of a small intestine. Closely associated with the capillary (3) and sectioned in a longitudinal plane is a mast cell with dense granules (5) in its cytoplasm and a red-staining nucleus. The capillary (3) is packed with red blood cells (6). Because the lumen of the capillary is about the size of a red blood cell (RBC), the RBCs in its lumen are lined up in a row. Located above the capillary (3) is a larger vessel, a venule (2), sectioned in a transverse plane and also packed with RBCs. Surrounding the blood vessels (2, 3) are numerous adipose cells (1) with their lipid contents washed out during slide preparation. Also present are the dense layers of blue-staining collagen fibers (4) and fibrocytes (7) that are closely associated with the blood vessels and the capillaries.  Loose Connective Tissue Collagen fibers -predominate in loose connective tissue, course in different directions, and form a loose fiber meshwork. The fibroblasts - are the most numerous cells in the loose connective tissue and may be sectioned in various planes, so that only parts of the cells may be seen. Also present in loose connective tissue are blood cells such as the neutrophils with lobulated nuclei, eosinophils with red-staining granules, and small lymphocytes with dense- staining nuclei and sparse cytoplasm. The fat (adipose) cells appear characteristically empty with a thin rim of cytoplasm and peripherally displaced flat nuclei. Dense Irregular and Loose Irregular Connective Tissue (Elastin Stain) The elastic fibers have been selectively stained a deep blue using the Verhoeff method. Using Van Gieson stain as a counterstain, acid fuchsin stains collagen fibers red. Cellular details of fibroblasts are not obvious, but the fibroblast nuclei stain deep blue. Blood vessels are also present. Loose Irregular and Dense Irregular Connective Tissue The collagen fibers in both types of tissues are large, typically in bundles, and sectioned in several planes because they course in various directions. In the dense connective tissue , the fibroblasts (nuclei) are often found compressed among the collagen fibers. In the loose connective tissue , the collagen fibers are less compressed and the fibroblasts are more visible. Also illustrated are capillaries a small venule an eosinophil with lobulated nucleus, lymphocytes with large round nuclei without visible cytoplasm, a plasma cell , and numerous adipose cells.  Dense Regular Connective Tissue: Tendon (Longitudinal Section) Dense regular connective tissue is present in ligaments and tendons. Shown here is a section of a tendon in the longitudinal plane showing the regular arrangement of the collagen fibers. The collagen fibers are arranged in compact, dense parallel bundles between which are thin partitions of looser connective tissue that contain parallel rows of fibroblasts. The fibroblasts have short processes (not visible here) and nuclei that appear ovoid when seen in surface view or flat and rodlike in lateral view. Dense irregular connective tissue with less regular fiber arrangement than in the tendon surrounds and partitions the collagen bundles as the interfascicular 180 connective tissue. Here are also found fibroblasts and numerous blood vessels, such as this arteriole , that supply the connective tissue cells.