组胚introduction and epithelium单击此处编辑母版标题

1、HistologyThe nine characteristics of life1 1 结结构构有有序序2 2 适适应应3 3 代代谢谢4 4 运运动动5 5 反反应应6 6 生生殖殖7 7 发发育育8 8 遗遗传传9 9 进进化化O Or rd de er rA Ad da ap pt ta at ti io on nM Me et ta ab bo ol li is sm mM Mo ov ve em me en nt tR Re es sp po on ns si iv ve en ne es ss sR Re ep pr ro od du uc ct ti io on nD De e

2、v ve el lo op pm me en nt tG Ge en ne es sE Ev vo ol lu ut ti io on nChapter 1 introductionChapter 1 introduction4What is histology A science studying human bodys microstructure and the relationship between the structure and functions There are four levels that the subject concerned cells tissues or

3、gans and systems Chapter 1 introductionChapter 1 introduction cell- - the basic structural and functional unit tissue-cells and intercellular materials in special way make up the mass four main type of tissue: epithelium connective tissue muscular tissue and never tissue organ- four tissues are arra

4、nged orderly to carrying certain functions system- several organs with related functions consist a kind of system The benefit bridge subject of anatomy,biochemistry,physiology and pathology. If you want to master those subjects, you must have knowledge of the subjects. Histology will introduce the s

5、tructures and functions of organelles and cells. Only understanding the normal structures of cells and tissues,the later study task become easier and more effective. It is impossible to study the abnormal before the normal is known. Light microscopy 1 1 Preparation of tissues Preparation of tissues

6、The routine histological preparation and examination is a paraffin sectioning stained with hematoxylin and eosin (H-E). The way of the studyThe way of the study4 1 Obtaining the specimen The fresh tissues are cut into small cubic pieces (no more than 1cm) in size. 2 Fixation The tissues are rapidly

7、fixed by immersing them in chemical fixative to preserve their structural organization. Procedures of the preparation:Procedures of the preparation: 3 Dehydration The purpose of dehydration is to replace the water in tissues by alcohol. 4 Clearing The purpose of clearing is to replace alcohol and tr

8、ansparentize tissues,and to prepare paraffin embedding. 5 Embedding the tissues and melted paraffin are poured into a mold and allowed to cool and harden. 6 Sectioning With a paraffin microtome, the embedding materials are cut into several micrometer thick sections. Prior to staining, paraffin secti

9、on are dewaxed with xylene and rehydrated with alcohol. Then sections are stained firstly with hematoxylin . The later stage are stained with eosin. H-E stainingH-E staining Hematoxylin is a basic dye which can binds acidic components (nuclear chromatin) of cells and tissues and show a bluish purple

10、 color. Generally, the components by haematoxylin staining are called basophilic. Eosin as an acidic dye binds to basic constituents of cells and tissues and gives a pink color. The characteristic of the constituents binding eosin are termed acidophilic Except paraffin sections, research tissues may

11、 also be cut with a freezing microtome. Due to preparing frozen sections do not need to dehydration, clearing and paraffin embedding, some chemical components and enzymes may be better preserved. Another common preparation is smear which are often used for examination of blood or other secretions. E

12、lectron microscopyElectron microscopy 1 1 Transmission electron microscopy TEM The TEM uses a beam of electrons with short wave-lengths in place of visible light.The electron beam passes through a series of electromagnetic lenses for focusing and magnification instead of the glass lenses in the ligh

13、t.Electron microscopyElectron microscopy The electron microscope permits visualization of the internal structure of cells and tissues as well as extremely small structures within cells or in intercellular spaces. Structures identified with the electron microscope are called ultrastructures.Electron

14、microscopyElectron microscopy 2 Scanning electron microscopy SEM A specimen for SEM examination is coated with a layer of platinum or gold. Then a beam of electrons scans the surface. As the electron beam bombards the surface of the specimen, secondary electrons are emitted from the surface and coll

15、ected by a detector. The signals from many points create an image on a cathode ray tube, revealing the three-dimensional surface architecture of cells and tissues. 1 Histochemistry and cytochemistry2 Immunohistochemistry and Immunocytochemistry3 In situ hybridization4 Vital staining 5 Cell and tissu

16、e culture Chapter 2 EpitheliumType of tissue and their origins4Cells are highly organized, but they do not function as isolated units in body. They work together in groups called tissue.4A tissue is a group of cells that usually have a common embryonic origin and function together to carry out speci

17、alized activities.4The structure and properties of a specific tissue are influenced by such things as the nature of the extracellular material that surrounds the tissue cells.4Body tissue can be classified into four principal types : 1 Epithelial tissue, which covers body surfaces;lines hollow organ

18、s,body cavities, ducts;and forms glands. 2 Connective tissue, which protects and supports the body and its organs;binds organs together,stores energy reserves as fat;and provides immunity. 3 Muscle tissue, which is responsible for movement and generation of force. 4 Nervous tissue, which initiates a

19、nd transmits action potentials (nerve impulses) that help coordinate body activities. epithelium 4Epithelium may be divided into two groups: (1) covering epithelium and (2) glandular epithelium4Covering epithelium forms the superficial layer of the skin and some internal organs. It forms the inner l

20、ining of blood vessels, ducts, body cavities, and the interiors of the respiratory, digestive, urinary, and reproductive systems. epithelial tissue4Glandular epithelium constitutes the secreting portion of glands, such as sweat glands and the thyroid gland. 4Epithelial tissue also combines with nerv

21、ous tissue to make up special sense organs for smell, hearing, vision, and touch.General Features of Epithelium 1 The tissue consists largely or entirely of closely packed cells with little extracellular material between adjacent cells. 2 Epithelial cells have an apical (free) surface, which is expo

22、sed to a body cavity, lining of an internal organ, or the exterior of the body, and a basal surface, which is attached to the basement membrane. 3 Epithelium are avascular , The exchange of materials between epithelium and connective tissue is by diffusion. 4 Epithelium have a nerve supply. 4The cel

23、ls of most epithelial tissue are continually replaced by mitosis of progenitor cells. Thus epithelial tissue is constantly being regenerated.4The Functions of epithelium: protection, filtration, lubrication, transportation, digestion, absorption, sensory receptor, reproduction, secretion and excreti

24、on.Covering (lining) Epithelium41 Simple epithelium Only a single layer of cells which located in the area where activities such as diffusion, osmosis, filtration, secretion, and absorption occur. 4 2 Stratified epithelium contains two or more layers of cells that protect underlying tissue in the ar

25、eas where there is considerable wear and tear. 43 Pseudostratified epithelium contains one layer of a mixture of cell shapes. The tissue has a multilayered (stratified) appearance because the nuclei appear at different levels and not all cells reach the surface are either ciliated or secrete mucus.4

26、Four basic shapes of the epithelial cells : 1 Squamous cells are flat and attach to each other like tiles. Their thinness allows for rapid movement of substances through them. 2 Cuboidal cells are thicker, being cube or hexagon shaped. They produce several important body secretions. They may also fu

27、nction in absorption of fluids and other substances, such as digested foods in the intestines 3 Columnar cells are tall and cylindrical, thereby protecting underlying tissues. They may also be specialized for secretion and absorption. 4 Transitional cells readily change in shape due to distention, e

28、xpansion, or movement of body parts.Simple Epithelium4Simple squamous epithelium This consists of a single layer of flat cells. The nucleus of each cell is oval or spherical. Since simple squamous eithelium has only one layer of cells, it is highly adapted for diffusion, osmosis, and filtration. Sim

29、ple Epithelium4Simple squamous epithelium that lines the heart, blood vessels, and lymphatic vessels and forms the walls of capillaries is known as endothelium. Simple squamous epithelium that forms the epithelia layer of serous membranes is called mesothelium. 4Simple Cuboidal epithelium The cells

30、of the epithelium is cuboidal shape. The nuclei are usually round. the location and functions : Covers surface of ovary and lines kidney tubules and smaller ducts of many glands. Secretion and absorptionSimple Epithelium4Simple columnar epithelium The cells appear rectangular with oval nuclei. some

31、type of the epithelium contains microvilli and goblet cells. Microvilli serve to increase the surface area of the cells. Goblet cells are modified columnar cells that secrete mucus.4 location: Lines the gastrointestinal tract from the stomach to the anus, ducts of many glands and gallbladder. 4 func

32、tions: Secretion and absorption4Pseudostratified ciliated columnar epithelium Even though all the cells are attached to the basement membrane in single layer, some cells do not reach the free surface. The nuclei of the cells are at varying depths. 4the cells that reach the surface either secrete muc

33、us or bear cilia that sweep away mucus and trapped foreign particles and elimination from the body. 4 the Location and functions: lines most of upper respiratory tract. Secretion and movement of mucus by ciliary actionStratified epithelium4Stratified squamous epithelium In the superficial layers of

34、this type of epithelium, the cells are flat, whereas in the deep layers, cells vary in shape from cuboidal to columnar. 4Stratified squamous epithelium exists in two forms: keratinized and nonkeratinized. 4nonkeratinized Stratified squamous epithelium : oral cavity, esophagus, vagina.4keratinized St

35、ratified squamous epithelium : epidermis of skin.4Stratifited columnar epithelium This type of tissue is uncommon in the body. Usually the basal layer consists of shortened,irregular polyhedral cells. Only the superficial cells are columnar in form. Location of the epithelium: urethra of male, porti

36、on of conjunctiva of eye. Functions: Protection and secretion 4Transitional epithelium The epithelium is variable in appearance, depending on whether it is relaxed or distended. Because of this capability,transitional epithelium lines hollow structures that are subjected to expansion from within, such as the urinary bladder. Glandular epithelium4The function of glandular epithelium is secretion. A gland may consist of one cell or a group of highly speciali