Introduction Histology is a science which studies the normal microstructure of the human body and the relationship between the body’s structure and function. cells are the smallest structural and functional unit of human body

Key points of this class Methods employed in Histology

1. Histology 2. Embryology Histo=Tissue Logy=Study Logy= study Embryo= unborn or unhatched offspring Logy= study

What we will learn in this course Tissue: 4 basic tissues Organ system

Why it is important to learn histology? To recognize normal tissue and cells To acquire basic skill which you will use throughout your career!!!

What you need to do Look Think Compare Remember Idealized images

2. Basic methods of histology Observation of histological slides Procedure: Specimen Fixation Embedding Sectioning Staining Observation

Fixation solution (fixative) LM--- 4% formaldehyde – Fixative and antibacterial agent EM--- glutaraldehyde followed by osmium tetroxide

Embedding Ethanol----dehydration Xylene----clearing Paraffin----embedding

Sectioning Microtome thickness 2~10 μm Units M,mm,μm,nm 1nm=0.001μm=10-6mm=10-9m

Microtome

Staining Basophilia , Acidophilia, Neutrophilia, metachromasia Basic dyes: toluidine blue, methylene blue, hematoxylin (blue) Acid dyes: orange G, eosin, acid fuchsin (pink) common staining: Hematoxylin & Eosin Specific staining: silver

Hematoxylin & Eosin (H&E) H&E is the most commonly method in histological study Hematoxylin Blue Eosin Pink

Hematoxylin Eosin H&E

3. Microscopes Light microscope Specific microscope (1). Phase-contrast microscope (2). Differential interference microscope (3). Fluorescence microscope (4). Confocal microscope

Electron microscope EM Transmission - plain Scanning – platinum or gold layers, 3 dimensional

Photograph of the transmission electron microscope.

Schematic view of a transmission electron microscope with its lenses and the pathway of the electrons. CCD, charged coupled device.

Schematic view of a scanning electron microscope.

4. Other methods A. Autoradiography B. Histochemistry and cytochemistry PAS (periodic acid Schiff reaction) Feulgen reaction C. Immunocytochemistry Antigen and antibody reaction D. In situ hybridization DAN or RNA single strand complementary

Other methods (continue) E. Cell culture —stem cells F. Transgenic animal G. Micromanipulation and cloning

Summary 1. Histology is the study of the tissues of the body and of how these tissues are arranged to constitute organs. 2. Histology=Microscopic anatomy  3. Section preparation and HE staining  4. Other methods