General Histology and Histotechnique (1st semester; 2012-2-13)

CONNECTIVE TISSUE Characteristics: - Have intercellular spaces - Cells scattered in matrix - Wide variety of cells most abundant - Vascular - From mesoderm - Lie below basement membrane Functions: 1. Binds together, supports and strengthens other body

tissues 2. Protects and insulates internal organs. 3. Compartmentalizes structures such as skeletal

muscles. 4. The major transport system within the body. 5. The major site of stored energy reserves; for fat cells. Connective Tissue: Embryonic origin - blast - cytes – mature cells; form the connective tissues.

Two basic elements:

1. Cell 2. Matrix

Types of Cells

1. Fibroblasts - Large-flat-spindle shaped cells with branching

processes. - Present in all - Most numerous Function: - To secrete the proteins needed for fiber synthesis. - Components for intercellular matrix.

2. Macrophages/Histocytes - Developed from monocytes (WBC) - Irregular shape

Function: - To engulf those bacteria – cellular debris;

phagocytosis Two types:

a. Fixed Macrophage - it resides in a particular tissue only Ex.: Alveolar macrophages in the lungs; spleen b. Wandering macrophage - Roamed the tissues and then gather at sites of

infection/inflammation. 3. Plasma Cells - Small and round/irregular shape - Developed from lymphocytes - Secretes antibodies

Proteins that attacking on foreign substances in the body.

Important in Immune System. Location: GIT, Mammary gland 4. Mast Cells - Abundant alongside of Blood vessels that supply

connective tissue. - Produce Histamine

A chemical that dilates small blood vessels

Especially during the reaction in the injury.

5. Adipocytes (fat cells) - May form small clusters or aggregates in loose

connective tissue. - Store lipids and form adipose tissue.

Functions: It Protects, insulates and cushions organs of the body. 6. WBC - Not found insignificant numbers in connective

tissues - When there is a significant numbers of WBC –

Abnormality - Increase number in response to allergic condition

during parasitic invasion.

General Histology and Histotechnique (1st semester; 2012-2-13)

Neutrophil – Increase number at site of infection. 7. Chondrocytes - Mature cells that form cartilages.

8. Osteocytes - form the bones 9. Hematopoietic cells - Form the Blood cells 10. Undifferentiated mesenchyma - Potential to differentiated into adult cell types Connective tissue MATRIX Matrix - Maybe fluid, semi-fluid, gelatinous, fibrous, or

calcified Function: To prevent tissue cells from touching one another. Consists of: A. Ground Substance - Highly hydrated gel which the cells and fibers of

connective tissue are embedded - Intercellular substances Made up of: 1. Hyaluronic Acid - Viscous - Slippery substances Function: - To bind cells together - To lubricate - It helps maintain the shape of eye ball

Hyaluronidase - It breaks apart the hyaluronic acid, and causes the

ground substance to become watery. Location: WBC – produces hyaluronidase to move connective tissue. - Produce by sperm cell – to fully penetrate the eggs

during fertilization - Produce by bacteria for them to spread in

connective tissues 2. Chondroitin Sulfate

- Jelly-like substance that provide support and adhesiveness in cartilages, bones, skin, and blood vessels.

Dermatan sulfate - found in skin, tendon, Blood vessels, Heart bulbs Keratan sulfate – Found in bone, cartilage, cornea of the eye. 3. Adhesion Protein - Responsible in linking components of ground

substances to each other and to the surfaces.

Fibronectin – principal adhesion protein of connective tissue Ex.: - It binds halogen, fibers, and ground substances and

cross-linked them together. - It attaches cells to ground substances B. Fibers - Strengthen and support connective tissues Types: 1. Collagen Fibers “colla” – glue

- Appear as white fiber - Most abundant connective fibers - Contain a protein substance known as collagen. - For flexibility at a High Tensile Strength

5 types of collagen fibers:

Types Location Function

1. Type 1 Skin, bone tendon, ligament, dentine, sclera of the eye, organ capsules

Accounts for 90% of the total body collagen; provide resistance to force tension and stretch.

2. Type 2 Cartilage (hyaline and elastic) notochord, invertebral disc.

Provide shape & resistance to deformation

3. Type 3 Uterus, liver, spleen, kidneys and lungs, smooth muscles, blood vessels and fetal skin.

Provide structural support and elasticity

4. Type 4 Basal lamina of epithelial and endothelial cells, kidney

Provide support and filtration barrier

5. Type 5 Basal lamina of smooth and skeletal muscle cells, glial cells, placental epithelium

Provide support.

General Histology and Histotechnique (1st semester; 2012-2-13)

2. Elastic fibers - Known a Yellow fiber - Smaller diameter than in collagen - Branched to joined together to form network within

a tissue - Protein – Elastin

Surrounded by glycoprotein – Fibrillin – essential to the stability of elastic fibers.

Function: - For strength and stability Location: Skin, Blood vessels (walls), lung tissues 2 types:

1. Stretched 2. Relaxed

3. Reticular fibers - Consists of collagen and protein of glycoprotein - Produced by fibroblasts - Thinnest and form branching network

Functions: - Provide support and strength - Provide support to the walls of Blood vessels

- It forms a network around fat cells, nerve cells/fiber, skeletal & muscle cells.

- Forms the Stroma Meaning “bed/covering” Supporting framework of many soft

organs. - Helps form the basement membrane Location: boundary of C.T. and epithelial, around blood vessels, nerves, hematopoietic tissues such as bone marrows, liver, spleen Classification of Connective Tissue I. Embryonic - Present in embryos and fetus

a. Mesenchyme - Exclusively found in embryo - This tissue were all types of connective tissue arise - Composed of irregular cell – mesenchymal cell - Contains a semifluid ground substance - Contains a delicate reticular fiber Location: found under skin and along developing bones of embryo, in adult connective tissues especially blood vessels.

b. Mucous / Warton’s jelly - Consists of a widely scattered fibroblast - Viscous ground substance and jelly-like collagen

fibers Location: Umbilical cord Function: For support

General Histology and Histotechnique (1st semester; 2012-2-13)

II. Mature 1. Loose - Fibers are loosely woven a. Areolar - One which is widely distributed in the body - Forms the subcutaneous layer Layer of a tissue that attaches the skin to the

underlying tissues and organs. - Most common connective tissues in all

invertebrates. - One of the component of Basement membrane - Consists of Macrophages, mast cells, Fibroblasts

Function: - Separates muscles

b. Adipose - Adipocytes; fat cells - Derived from fibroblast - Good insulator (reduced heat loss) - Widespread in fetus & infants - Only small amount in adult

Function: for storage of triglycerides Location: found I subcutaneous layer deep to skin, around heart and kidneys, yellow marrow of long bones, padding around joints and behind eyeball in eye socket.

General Histology and Histotechnique (1st semester; 2012-2-13)

c. Reticular - Consists of reticular fibers/reticular cells - Forms stroma of organs - Binds together smooth muscle tissue cells - Contains collagen, elastic & reticular - Cells – fibroblast, macrophage, plasma cells,

adipocyte, mast cells

Location: Stroma (supporting framework) of liver, spleen, lymph nodes; portion of bone marrow; reticular lamina of basement membrane, around blood vessels and muscle, subcutaneous layer of skin, lamina propria of mucous, nerves.

2. Dense - More numerous thicker and denser fibers - With few cells a. Dense regular connective tissue - Matrix-Shiny white - Bundles of collagen fibers

Function: Provide strong attachment between various structures. Location: Tendons (muscle to bone); Ligaments (bone to bone); Aponeurosis (muscle to muscle/ muscle to bone)

b. Dense irregular connective tissue - Collagen fiber (randomly arranged) - Few fibroblast

Location: Fascia (tissue beneath skin and around muscles and other organs); reticular region of dermis of skin, periosteum of bone, perichondrium of cartilage, joint capsules, membrane capsules around various organs (kidneys, liver, testes, lymph nodes), pericardium of the heart and heart valves.

General Histology and Histotechnique (1st semester; 2012-2-13)

c. Elastic connective Tissue - Branching elastic fiber - Cell - fibroblast - Allows stretching of various organs

Location: Lung tissue, walls of elastic arteries, trachea, bronchial tubes, true vocal cords, suspensor ligament of penis, and ligaments between vertebrae.