Histology,Introduction,Yu Xiangmin (于向民） Department of Histology and Embryology,Definition: A science: study normal micro-structure(微细结构)& its related function of human body. 4 structural levels: Cell: the smallest structural & functional unit. Tissue(组织): groups of cells (similar in morphology or related in function)intercellular materials 4 types of fundamental tissue epithelium 上皮组织 connective tissue 结缔组织 muscular tissue 肌组织 nervous tissue 神经组织,Organs:器官organizations of various kinds of tissues in particular ways & perform a specific function. System:系统formed by several function-related organs which together perform a continuous physiological function. For example: digestive system,Why do we study histology ?,To complete the knowledge of human bodys structures-from gross to microscopic Be able to understand how the different tissues function-the basis of physiology Can find the diseases only after the normal is known-the basis of pathology It is also a foundation of clinic sciencesfor a good doctor needed in future,Investigative methods of histology,I. Light microscopy,l,1. Tissue preparation A. paraffin section preparation石蜡切片术 Specimen取材: as fresh as possible Fixation固定: fixative: formalin solution; purpose: to preserve the structural organization Dehydration脱水: replace the water in the tissue by alcohol Clearing透明: replace the alcohol by xylene Embedding包埋: replace the xylene with melted paraffin Sectioning & mounting切片,B. Frozen section: Better for preserving chemical components (e.g. enzymes) Freezingcryostatstaining C. the others: Smear preparations: for blood etc; Grind preparations: for bone,2. Staining染色 Purpose:To make tissue section for observation. H-E Staining: Hematoxylin:苏木精 basic dye, bluish color Eosin:伊红acid dye, pink color Basophilic:嗜碱性components stained with basic dye (H); bluish（nuclear chromatin) Acidophilic:嗜酸性components with an affinity for acidic dye (E); pink (cytoplasm & collagen fiber),Neutrophilic:中 性 do not stain with both basic and acid dyes Argyrophilia:嗜银性 those with an affinity for silver, dark-brown color,Fluorescent staining shows the apoptosis in human HL-60 cells,Silver staining of the neuron and the bile canaliculi,Transmission Electron Microscope (TEM)透射电镜 Using a beam of electrons (short wave-lengths) instead of visible light. Section preparation: similar to those for L.M mainly, plastic instead of paraffin, 50-70nm thick, heavy metal salts instead of HE. Resolution: 0.1-0.5nm Ultrastructrue:超微结构The structure in EM Electron-dense电子密度高 electron-lucent电子密度低,Electron Microscopy,Transmission Electron Microscope,Diagrams of TEM,2. Scanning Electron Microscope (SEM) 扫描电镜 Sowing the 3 dimensional surface Architecture of cells and tissues Resolution: 5nm,JEOL扫描电子显微镜,III. Histochemistry & Cytochemistry 组织化学术,Reveal the chemical composition in situ (e.g. proteins, a.a., nucleic acid, lipids, enzymes etc.) with chemical, biochemical methods. The product of chemical reaction should be insoluble / colored / electron- scattering, & be seen in LM or EM,polysaccharide + HIO4 (hydroxyl group) (oxidise) Aldehyde group + Shiffs reagent (colorless) Purplish red depositor,For instance: PAS(Periodic Acid Schiff) reaction: for manifesting polysaccharide 多糖 (糖原）,PAS reaction in the goblet cell,IV. Immunocytochemistry免疫组织化学,Based on antigen binds to specific antibody. Tissue section with Antigen + labelled antibody labelled Ag-Ab complex,Fluoresceinlabelling,enzyme labelling,colloidal gold labelling,V. tissue culture 组织培养 VI. in situ hybridization (ISH) nucleic acid molecular hybridization 原位杂交术,Use nucleotide probe to check target fragment of intracellular DNA or mRNA in situ, in order to study the gene expression.,Expression of PSA and PSAmRNA in human prostate (histochemistry & ISH),The method in learning histology,Combination of the 2 dimentional structure with 3 dimentional,Combination of the theory with practice Combination of the structure with function Concern the dynamic change,Questions for review,What is the H &E staining? Describe basophilic, acidophilic, neutrophilic? What does PAS positive means?,