Histology Instructors: Faris Mohammednoor Altaf MT. MS. Ph.D. د. فارس محمد نور سعيد ألطف Phone# ext Mohammad Afzal Khan M.B.B.S., M.Phil. Phone# ext Text/Atlas: - Basic Histology Text and Atlas, Luiz Carlos Junqueira and Jose Carneiro, 11th Ed., McGraw-Hill Publishing, Color Atlas of Histology (Paperback) by Leslie P Gartner, James L Hiatt 4 th Ed. (April 1, 2005)

Introduction The name "Histology" is derived from the Greek word for a tissue "Histos", and "-logos" = the study of. Four fundamental tissues are recognized: epithelial tissue, connective tissue, muscular tissue, and nervous tissue. Tissues are made of cells and extracellular matrix. Intense interaction between cells and matrix cells and extracellular matrix form a continuum that functions together and reacts to stimuli and inhibitors together The small size of cells and matrix components makes histology dependent on the use of microscopes

BASIC TECHNIQUES Preparation of histological sections 1. Fixation 2. Embedding 3. Microtomy 4. Staining 5. Permanent Mounting Frozen sections Total preparations In some cases the tissue to be examined is a very thin membrane. Cell Smears blood or bone marrow, epithelial cells (e.g. from the oral cavity, cervix uteri).

STAINING TECHNIQUES 1. Hematoxylin and Eosin (H&E) – The Hematoxylin is a basic dye that stains acidic components of cells a blue color (basophilia). Hematoxylin stains the nuclei of cells, and the RER of the cytoplasm – Eosin is an acidic dye that stains the basic components of the cells a reddish-pink color (acidophilia). Most of the cytoplasm of cells is stained by eosin. Bone matrix is also stained by eosin. 2. Periodic acid-Schiff (PAS) staining – mucus, the basal lamina, glycogen. 3. Orcein – elastic fibers a dark brown-purple color. 4. Osmium tetroxide – Osmium is used to stain lipids a dark black color. myelin of myelinated nerves, or lipid droplets in the liver or steroid-secreting cells. 5. Oil Red O – Oil Red O is used to stain lipids a red-orange color in unfixed frozen sections. 6. Toluidine blue – so-called metachromatic stain. It is a blue stain that stains specific components of tissues a purple color. This change in staining color is known as metachromasia. Metachromasia is seen in the matrix of hyaline cartilage, or in the granules of mast cells. 7. Impregnation – Silver impregnation techniques are also widely used to demonstrate reticular fibers.

Light Microscopy

Phase-Contrast Microscopy

Polarizing Microscopy

Fluorescence Microscopy

Electron Microscopy

The Cell The Cytoplasm Nucleus

Plasma Membrane

Function of PM

Mitochondria

Ribosomes

Endoplasmic Reticulum

Golgi Complex

Lysosomes

The Cytoskeleton Microtubules Intermediate Filaments Actin Filaments

The Cell Nucleus