Introduction
What is Histology? Why to study Histology? Techniques on Histology How to study Histology?
Histology and Embryology Histology is a science which study the microstructure and the relationship between the structure and function of human being. Embryology is a science which study the processes and regulations of development of human fetus.
Histology： /histo-tissue /ology-study of ,or knowledge of So, histology means the knowledge of tissue, is a branch of Anatomy a science to study the fine structure associated with its function in the human body.
smallest unit of structure and function of body Cell : smallest unit of structure and function of body tissue: group of cell+extracellular metrix organ: several tissues combined orderly system:organs Which have related function get together.
four kinds of basic tissues epithelium connective tissue muscular tissue nervous tissue
Techniques on Histology Development of histology depends on the development of techniques. microscope light microscope(LM) electron microscope(EM)
the measuring unit LM : um EM : nm
paraffin section preparation 1. Tissue preparation paraffin section preparation The most routine one is paraffin section stained with hematoxylin and eosin(H&E) The steps: a. Obtaining the specimen: fresh, small pieces ( less than 5mm3)-tissue block b. Fixation: to avoid digestion and to preserve the structure,use fixatives( formalin ) c. Dehydration: use ethyl alcohol to get rid of water of tissue and cell d. Clearing: use xylene to get rid of alcohol
e. Embedding: Embedding materials include paraffin and resin. Paraffin is used routinely . firstly, heat the paraffin, make it melt, then put tissue block into melted paraffin, allow paraffin harden, the tissue block is embedded in. f. Sectioning: use microtome to cut the tissue into 3-8um thick sections, then put them on glass slides
2. Staining ( H&E stain) ---Hematoxylin: basic dye, combines with acidic components, make them appear blue colour basophilic
---Eosin: acidic dye, combines with basic components, make them appear pink acidophilic
electron microscope ( EM) TEM SEM
Histochemistry 1) General Histochemistry Combine histological methods with chemical or biochemical methods, make some compositions of tissue or cell become insoluble, coloured or electron-dense, to show those chemical compositions of tissue or cell in situ, such compositions includes protein,amino acid, nucleic acid, lipid and polysaccharides.
Periodic acid schiff reaction(PAS reaction): polysaccharides and glycogen
2) immnohistochemistry:
3) in situ hybridization
Autoradiograph Tissue culture and cell culture
How to study Histology?
Cell of Human body