M. / L / Nayak Textbook of Histology for Undergraduates

2. Auflage 2024
ISBN: 978-93-95390-79-8
Verlag: Thieme
Format: EPUB
Kopierschutz: Adobe DRM (»Systemvoraussetzungen)

E-Book, Englisch, 286 Seiten, ePub

A Dynamic Study Companion to Master Core Concepts in Histology. Now in a New Edition!The current edition provides competency-based approach for the undergraduates. The title elucidates fundamental concepts in histology along with an exam-oriented approach.Salient featuresMapping of competencies and objectives to the content for all the topics.Functional histology has been provided correlating with the normal histology of the organ.Additional slides which are part of competency-based curriculum have been included.Additional flowcharts have been incorporated.MCQs have been added as part of assessment.Microscopic images of slides have been revised based on feedback received from readers.Separate section on frequently confused slides has been added to improve the learning outcomes and assessment scores in exams. This print book includes complimentary access to a digital copy on https://medone.thieme.com.   Publisher's Note: Products purchased from Third Party sellers are not guaranteed by the publisher for quality, authenticity, or access to any online entitlements included with the product.

Autoren/Hrsg.

M., Sangeeta

L, Varalakshmi

L, Varalakshmi K

Nayak, Jyothi

Nayak, Jyothi N

Fachgebiete

• Medizin | Veterinärmedizin Medizin | Public Health | Pharmazie | Zahnmedizin Vorklinische Medizin: Grundlagenfächer Histologie

Inhaltsverzeichnis

1. Microscope 2. Tissue Preparation 3. Epithelium 4. Glands 5. Connective Tissue 6. Cartilage 7. Bone 8. Muscular Tissue 9. Nervous Tissue 10. Circulatory System 11. Lymphatic Tissue 12. Integumentary System 13. Placenta and Umbilical Cord 14. Oral Cavity 15. Gastrointestinal Tract 16. Liver, Gall Bladder, Pancreas 17. Respiratory System 18. Urinary System 19. Male Reproductive System 20. Female Reproductive System 21. Endocrine Glands 22. Central Nervous System 23. Special Senses

Leseproben

3 Epithelium Competency AN65.1: Identify epithelium under the microscope and describe the various types that correlate to its function. AN65.2: Describe the ultrastructure of epithelium. Specific Learning Objectives a.Classify epithelial tissue based on the shape of cells, number of layers, and surface modifications with suitable examples. b.Identify, differentiate, and draw the microstructure of the different types of epithelia. c.Correlate the characteristics of particular epithelia to their function and their essential features including junctions, apical modifications. Introduction •Epithelium covers the body surfaces, lines the body cavities, and forms the secretory portions of glands and their ducts. •It is developed from all the three germ layers, i.e., ectoderm, endoderm, and mesoderm. Epidermis of skin is derived from ectoderm, epithelium of digestive and respiratory tracts derived from endoderm, and endothelium and mesothelium derived from mesoderm. •It is avascular, deriving its nutrition from diffusion through the capillaries present in the surrounding connective tissue. •All epithelial cells are compactly arranged due to close apposition with one another by cell junction. •Basal surface of epithelium rests on thin basement membrane and free surfaces are directed toward lumen of an organ or outer surfaces of body. •They have a high capacity to regenerate after damage. Classification of Epithelium Depending on the number of cell layer and shape of surface cells, the epithelium is classified as follows: •Simple epithelium (unilayered). •Stratified epithelium (multilayered). •Special type of epithelium is pseudostratified columnar epithelium. Simple Epithelium Simple Squamous/Pavement Epithelium •It is made up of a single layer of flattened cells resting on the basement membrane. •Each cell contains centrally placed oval nucleus (Fig. 3.1). •Function: Helps in diffusion of gases (e.g., alveoli of lung), filtration/dialyzing (e.g., Bowman’s capsule of kidney). Fig. 3.1 Diagram of simple squamous epithelium (H&E pencil). H&E, hematoxylin and eosin. Location of Simple Squamous/Pavement Epithelium •Alveoli of lung (Fig. 3.2). •Epithelium lining the blood vessels—endothelium. •Epithelium lining the ventricles and atria of heart—endocardium. •Epithelium lining the body cavities—mesothelium. Fig. 3.2 Simple squamous epithelium (alveoli of lung). Simple Cuboidal Epithelium •It is made up of single layer of cuboidal cells, where width and height of the cells are equal. •Cells contain centrally placed round nuclei (Fig. 3.3). •Function: Secretion (e.g., thyroid gland), absorption (e.g., tubules of kidney). Fig. 3.3 Diagram of simple cuboidal epithelium (H&E pencil). H&E, hematoxylin and eosin. Location of Simple Cuboidal Epithelium •Follicles of thyroid gland (Fig. 3.4), germinal epithelium of ovary, ducts of endocrine glands. •Pigment cell layer of retina. Fig. 3.4 Simple cuboidal epithelium (follicles of thyroid gland). Simple Columnar Epithelium •It is made up of a single layer of columnar cells, where length of cell is more than the width. •Cells contain elongated basal nuclei (Fig. 3.5). •Function: Located in areas requiring high absorption and secretion (e.g., gastrointestinal tract [GIT]). Fig. 3.5 Diagram of simple columnar epithelium (H&E pencil). H&E, hematoxylin and eosin. Location of Simple Columnar Epithelium •Lining of GIT—from stomach to anus, ducts of glands, uterus, etc. (Fig. 3.6). Fig. 3.6 Simple columnar epithelium (duodenum). Goblet Cells •The term “goblet” refers to “drinking glass.” •Goblet cells are modified columnar cells containing mucinogen granules between the nucleus and free surface. •Presence of mucinogen granules in the apical part makes it pale on staining. •Nucleus is flattened and located at the base of cells (Fig. 3.7). •They secrete mucus. Fig. 3.7 Goblet cell. Location of Goblet Cells •Lining epithelium and glands of intestine (Fig. 3.8), and lining epithelium of certain respiratory passages. Fig. 3.8 Goblet cells in large intestine. Stratified Epithelium Stratified Squamous Nonkeratinized Epithelium •It is composed of multilayered cells. •Basal layer of cells are columnar or cuboidal, resting on a basement membrane. These cells are rapidly dividing. •Intermediate layers are made up of polyhedral cells. •Superficial layers are made up of flattened squamous cells (living) and nonkeratinized (Fig. 3.9). •Function: Seen in areas subjected to wear and tear (e.g., esophagus/oral cavity). Fig. 3.9 Stratified squamous nonkeratinized epithelium (H&E pencil). H&E, hematoxylin and eosin. Location of Stratified Squamous Nonkeratinized Epithelium •Oral cavity, tongue (Fig. 3.10), esophagus, and vagina, cornea, anal canal. Fig. 3.10 Stratified squamous nonkeratinized epithelium (oesophagus). Stratified Squamous Keratinized Epithelium •It is similar to stratified squamous nonkeratinized epithelium except that the superficial cells lose their nuclei and are filled with substance known as keratin (Fig. 3.11). •Function: Protection (e.g., skin). Fig. 3.11 Stratified squamous keratinized epithelium (H&E pencil). H&E, hematoxylin and eosin. Location Stratified Squamous Keratinized Epithelium •Skin (Fig. 3.12). Fig. 3.12 Stratified squamous keratinized epithelium (thick skin). Stratified Cuboidal Epithelium •Two or more layers of cuboidal cells resting on basement membrane (Fig. 3.13). •Function: Secretion and protective barrier. Fig. 3.13 Stratified cuboidal epithelium (H&E pencil). H&E, hematoxylin and eosin. Location of Stratified Cuboidal Epithelium •Ducts of sweat gland (Fig. 3.15). Stratified Columnar Epithelium •Two or more layers of columnar cells resting on basement membrane (Fig. 3.14). •Function: Secretion and protective barrier. Fig. 3.14 Stratified columnar epithelium (H&E pencil). H&E, hematoxylin and eosin. Fig. 3.15 Stratified cuboidal epithelium (ducts of gland). Location of Stratified Columnar Epithelium •Larger ducts of glands and fornix of conjunctiva. Transitional Epithelium •It is a multilayered epithelium showing variations in its layers during stretched (two to three layers, Fig. 3.16) and relaxed condition (four to six layers, Fig. 3.17). •Basal cells are cuboidal or columnar. •Intermediate layers are made up of polyhedral or pear-shaped cells. •Superficial cells are dome-shaped or umbrella-shaped. Some cells may be binucleated with polypoid number of chromosomes. Fig. 3.16 Transitional epithelium (stretched) (H&E pencil). H&E, hematoxylin and eosin. Fig. 3.17 Transitional epithelium (relaxed) (H&E pencil). H&E, hematoxylin and eosin. Location of Transitional Epithelium •Epithelium lining the urinary bladder (Fig. 3.18) and ureter, hence, known as urothelium. Fig. 3.18 Transitional epithelium (urinary bladder). Functions of Transitional Epithelium •Superficial umbrella cells are held together by desmosomes, and its luminal surface is covered with eosinophilic glycoprotein particles or plaques, which act as a protective barrier and prevent the absorption of toxic substances from urine. •Stretchability of transitional...