Connective Tissue Fayez A. Elmabhouh Department of Biology

Introduction  C.T. are the most abundant of all the body tissues.  Large amount of Intercellular substance Consist of ground substance: Matrix and fibers.  C.T. serve to connect other tissues together and to skeleton.  Form the blood and the skeleton.  Support to the soft tissue.

Introduction  It also serve as framework, fill spaces, stores fat, provide protection against infections and help to repair tissue damage.

Classification of C.T. According to the nature of the ground tissue: 1. C.T. Proper: has gelatinous ground substance. 2. Skeletal tissues: a solid ground substance 3. Vascular tissues: fluid ground substance.

Connective tissue proper  Having an abundant Intercellular substance  Composed of 2 kinds of fibers lying in a jelly- like matrix.  They are found almost everywhere in the body.  C.T. proper divided into the following types:

1. Areolar C.T Matrix colorless, gelatinous and full of space. 2 kinds of fibers:  White fiber (collagenous): strong, non-branched and run in thick, wavy, branched bundles.  Yellow fiber (elastic): thin, single, straight and branched to form a network. Found in mesentery

Matrix consist of several types of cell:  Fibrocytes  Macrophage  Plasma cell  Mast cells  Adipose cell  Leukocytes or white cell

2. Fibrous C.T. White fiber predominate. They run in thick parallel bundle with C.T. cell in between which are strong and non-elastic. Present in tendon which attach muscles to bones.

3. Elastic C.T. The elastic fibers predominate. Present in elastic structures as the ligament which connect bones together.

4. Adipose C.T. Special type of areolar C.T. which is rich in fat or adipose cells filled with fat globules. It is common underneath the skin and around certain organs

5. Mucous C.T. This type characterized by having few stellate cells and few white fibers embedded in an extensive gelatinous matrix. It is found in the umbilical cord of mammals.

6. Reticular C.T. Contains a few short bundles of white fibers Extensive ground substance formed of lymph and numerous lymphoid cells. Such cells markedly branched, and the branches traverse each other forming a reticulum. Spleen and bone marrow.

Skeletal Tissues These tissues form the internal skeleton. Support the body and to which the muscles are attached. Two main types:  Cartilage.  Bone.

Cartilage It is semi-solid translucent tissue. Softer than bone. Component cells: cartilage cell or chondroblast They are large and found within capsules containing a fluid substance. Each capsule contains one, two or four cartilage cells. Matrix known as chondrin.

1. Hyaline Cartilage The matrix is clear and does not contain any fibers. This type exists in the trachea and at the end of long bone.

2. Fibro-Cartilage This type characterized by the presence of bundles of white fibers in the matrix. Exists in the intervertebral discs.

3. Elastic Cartilage This tissue elastic due to presence of elastic fibers in the matrix. Exists in the ear pineal.

Bone Bone is a sort of C.T. which has a solid matrix (ossein). This substance consists of large amount of calcium carbonate and calcium phosphate. These salts constitute 70-80% of the tissue weight.

Compact Bone The bone cell “osteocytes” found inside lacuna and joined together by canaliculi. Groups of osteocytes are arranged in concentric layers, each group surrounding a Haversian canal through which blood vessels and nerve fibers pass. The solid matrix (thin bone lamellae)

Vascular Tissue These are fluid C.T. Include blood and lymph. Blood is a highly specialized type of C.T. Red blood corpuscles (R.B.Cs or erythrocytes) White blood cells (W.B.Cs or leukocytes) Platelets.

Erythrocytes Round, biconcave and non-nucleated in man but many be nucleated on other animals.

Leukocytes Larger and fewer than erythrocytes and have nuclei of different form. Classified into two types according to presence or absence of granules in their cytoplasm. 1. Granulocytes. 2. Agranulocytes.

1. Granulocytes Have numerous granules in their cytoplasm. Distinguished into three types according to the staining affinity : 1. Eosinophils: Bilobed nuclei and granules stain with acidic dyes.

2. Basophils: have S shape nuclei and granules stain with basic dyes

3. Neutrophils: have a lobed nucleus consisting of 3-5 parts connecting by thin strand chromatin Cytoplasmic granules stain pinkish in neutral dyes.

Agranulocytes Two types: 1. Monocytes: Large and have kidney shaped nuclei.

2. Lymphocytes: Small or large. Have related large round nuclei which almost fill the whole cell.

Blood Smear