Welcome to learn 王旸 wang yang Division of Histology and Embryology AND 1

About myself 2

The arrangement and requirement of learning Histology and Embryology Normally, we have our class according to the schedule. Experimental lesson: start from the third week. Please do take your laboratory coat, text book, red and blue pencil, histological practice guide, report paper and student ID card with you, when we perform the experiments. The lab is located on the second floor of the building of tongde 同德楼 (4B 203— 206). Staff room ： 7A 210/215 (Teaching hours: 48 for theory, 44 for experiments) 3

Some requirements Do not be late, do not leave early, no absence. Please let me know if you could not attend class. Please take note and do review in time after class. Please hand in your experimental reports on time. Questions are welcomed if you have any in the process of studying. 4

INTRODUCTION Chapter 1 5

1. What is Histology/Embryology ? (What is cell/tissue?) 2. Why medical students should study histology? 3. What methods are used in the study of Histology ? Contents of Chapter 1 6

Histology (Greek words): /histo-tissue /logia-study of,or knowledge of So, histology means the knowledge, or science, of tissue, is a branch of Anatomy. Anatomy: ---gross anatomy —naked eye ---microscopic anatomy —microscope What is Histology? 7

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Histology: a science which studies the normal microstructure of the human body and the relationship between the body structures and functions. Research content: cell, tissue, organ and system. 9

Human body Systems Organs Tissues Cells cell: smallest unit of structure and function of body. tissue: a grouping of similar cells that work together to perform a single function : cells + extracellular matrix Four basic types of tissues: ↓ ---epithelium ---connective tissue ---muscular tissue ---nervous tissue organ: organized by several kinds of tissues in particular ways/in different proportion. system: formed by several organs with related functions. The Subject of studying histology ↓ ↓ 10

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Embryology: a science to study the normal development and congenital malformation of a human being in the maternal uterus. Sperm Ovum embryo fetus childbirthzygote 8w9-38w Conjoined twins 7w (Fertilization) 12

What is cell? More than 200 types of cells, Cell quantity of one person is about How many cells are there in our human body? 13

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What is Tissue ? Bichat, The tissues are formed by groups/collections of cells embedded in extracellular matrix. 16

Cell and extracellular matrix Cell is the structural and functional unit of all living organisms. Extracellular matrix: produced by cells consists of many kinds of molecules Function : carry away catabolites and transport nutrient to cell 17

Bichat, Epithelial tissue Connective tissue Muscular tissue Nervous tissue Four basic tissues 18

1.Epithelium * covers body surfaces * lines hollow organs * lines body cavities and duct * forms glands 19

2. Connective tissue: * protection and support * binding together (like glue) * immunity 20

3. muscle: movement and force 21

4. nervous: coordinates body activities 22

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? 2.Why medical students should study histology 24

First Year Histology & Embryology Anatomy Physiology Biochemistry Parasitology Pathology Microbiology Immunology Pathphysiology Pharmocology Basic medicine &Surgery Clinic (Medicine, Surgery, Gynecology, Pedology, etc.) Intern (exercitation) Graduate macrostructure microstructure 25

---Development of histology depends on the development of technique. ---Histology studies the microstructures. So, we should have the aid of microscope to study. Several types of microscopes are available. According to the light source used, microscopes can be basally classified as: light microscope(LM) electron microscope(EM) How to study it- histological methods 26

1. structure of Microscope LM EM ---useful magnification: 1500X 800,000X ---resolution: 0.2μm 0.2nm Resolving power– how close two structures can be and still be seen as separate. Micrometer( μm) 1μm=10 -3 mm=10 -6 meter Nanometer( nm) 1nm=10 -6 mm=10 -9 meter Two most common units used in histology 27

Microscopy microstructure ultrastructure Light microscopy Electron microscopy light microscopy use light microscope to study histology, which use illuminator as light source to illuminate the tissue sections. The structure observed with light microscope calls microstructure Conventional light microscope Phase contrast microscope Fluorescence microscope Electron microscopy use electron microscopye to study histology, which use the beam of electron replace the light to illuminate the tissue sections. The structure observed with electron microscope calls ultrastructure Transmission electron microscope (TEM) Scanning electron microscope (SEM) 28

conventional light microscope Mechanical part Optical part Illuminator condenser objective lens ocular lens (eyepiece) 29

Scanning electron microscope(SEM) Electrons scans the surface of the sample Nice 3-D effect 30

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Transmission Electron Microscope Electrons have short wavelength Electrons pass through sample show the ultrastructure of cells 32

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Preparation of tissues for LM Under the light microscope, tissues are examined via a light beam that is transmitted through the tissue. Tissue need to be thin enough and transparent. sections The most routine one is paraffin section stained with hematoxylin and eosin (H&E) 34

paraffin technique paraffin section The optimal thickness of light microscopic sections is about 5-8μm which is less than the diameter of a typical cell. 35

Obtainsample( ＜ 1cm) 1. Obtain the sample( ＜ 1cm) Fix the sample 2. Fix the sample Dehydrate 3. Dehydrate Clear 4. Clear 5 Embed 5 Embed SectionMount 6. Section and Mount Staining 7. Staining H.E. staining methods ( paraffin section) 36

Obtainsample/specimen 1. Obtain the sample/specimen Tissue blocks(tissue sample) can be obtained through biopsy( diagnostic sampling), surgical excision, or postmortem dissection. Tissue blocks(tissue sample) can be obtained through biopsy( diagnostic sampling), surgical excision, or postmortem dissection. cut ＜ 1cm in each dimension cut ＜ 1cm in each dimension Tissue blocks must be immersed in fixative immediately after removal. Tissue blocks must be immersed in fixative immediately after removal. 37

Clear 4. Clear Dehydrate 3. Dehydrate use alcohol to extract water in the specimen use xylene to remove alcohol As the specimen are infiltrated with xylene, they become transparent(clearing). Fix the sample 2. Fix the sample Purpose: To avoid tissue digestion by enzymes present within the cell or by bacteria and to preserve the structure and molecular composition as they had in the body. fixative: formaldehyde(FA) and paraformaldehyde(PFA) 5. Embed 38

5.Embed Firstly, heat the paraffin, make it melt, then put specimen into melted paraffin, and paraffin infiltrated into tissues. When paraffin cold, they become solid/hard. 39

Section 6. Section put embedded specimen on a microtome, which slices like a mini meat slicer, cut tissue into sections 5-10 μm thick. Mount Mount the sections on microscope slides. Unstained section 40

Staining 7. Staining The purpose of stain is to enhance nature contrast H&E(Hematoxylin and Eosin ) Most common : H&E staining (Hematoxylin and Eosin ) 41

basophilic ---basophila If the structure of a tissue or cell is easily stained by hematoxylin(basic dye),it is basophilic ---basophila blue/purple blue/purple Nucleic acids and ribosomes generally stain basophilically H&E H&E staining 42

And….. acidophilic---acidophila If the structure is easily stained by Eosin(acid dye), it is acidophilic---acidophila red/pink red/pink, Stains mitochondria, secretory granules,collagen, Extracelluar Matrix. H&E H&E staining 43

Using Hematoxylin and Eosin to stain the samples, the portion which are basophilic, can be stain blue or purple by hematoxylin, and the portion which are acidophilic can be stains red/pink by Eosin. H&E ★★ concept of H&E staining Neutrophilic: can neither be stained by H nor E 44

Methods of learning histology 1. Establishing concepts of three-dimension and dynamics 2. Paying attention to linkage between structure and function 3. Attaching importance to combination of theory and practice 4. Promoting study through hard-working and skills 45

SUM UP What is histology? The concept of cell and tissue Four basic tissue types Paraffin section technique HE staining (basophilic/acidophilic) 46

THANKS! 47