Module IІ. General Histology
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| MODULE IІ. General Histology. Content module 3. Histology of the general tissues. Practical class № 16. Duration of the practical class: 2 hours. Theme: The study of tissues. Epithelial tissues: covering epitelium. Professional Motivation: The epithelia are a diverse group of tissues, which, with rare exceptions, line all body surfaces, cavities and tubes. Epithelia thus function as interfaces between biological compartments. Epithelia interfaces are involved in a wide range of activities such as absorption, secretion and protection and all these major functions may be exhibited at a single epithelial surface. For example, the epithelial lining of the small intestine is primarily involved in absorption of the products of digestion, but the epithelium also protects itself from noxious intestinal contents by the secretion of a surface coating of mucus. Epithelial tissues have morphofunctional features which may be changed in some pathologic states, for example inflammation, dystrophia, dysplasia and metaplasia. Basic Level:
^ I. Objectives for Students’ Independent Studies You should prepare for the practical class using the existing textbooks and lectures. Special attention should be paid to the following:
Real – life situations to be solved:
Visual Aids and Material Tools: Students should be able to indicate elements in the electron micrographs: 1. Simple squamous epithelium (inner epithelium of the cornea). 2. Simple columnar epithelium (epithelium of the mucosa small intestine villi). 3. Pseudostratified columnar epithelium (epithelium of the trachea mucosa). 4. Straified squamous keratinized epithelium (epidermis). Students’ Practical Activities: Students must know and illustrate such histological specimens: Specimen 1. Simple squamous epithelium (mesothelium of the peritoneum). Stained with silver impregnation. In this specimen, the mesothelial lining of the peritoneal cavity has been stripped from the underlying connective tissues. This lining is supported by a thin basement membrane. The intercellular substance has been stained with silver thereby outlining the closely interdigitating cell boundaries. Epithelium is composed of flattened, irregularly-shaped cells. The nuclei have been stained with the dye, neutral red. Illustrate and indicate: 1. Nucleus. 2. Cytoplasm. 3. Cell’s boundaries.
Specimen 2. Simple cuboidal epithelium (renal tubules). Stained with haematoxylin and eosin. This specimen of the cells lining a small tubule in the kidney shows simple cuboidal epithelium in section. Although the boundaries between individual cells are indistinct, the nuclear shape provides an approximate indication of the cell size and shape. Epithelium is supported by the underlying basement membrane. Illustrate and indicate: 1.Basement membrane. 2. Epithelial cells: a) nucleus; b) cytoplasm. 3.Lumen of the tubule.
Specimen 3. Simple columnar pseudostraified ciliated epithelium (trachea). Stained with haematoxylin and eosin. Pseudostratified columnar ciliated epithelium may be distinguished from true stratified epithelia by two characteristics. Firstly, the individual cells of the pseudostratified epithelium exhibit polarity, that is the apical cytoplasm does not contain nuclei. Secondly, cilia are never present on stratified epithelia.Illustrate and indicate: 1. Basement membrane. 2. Ciliated cells. 3. Goblet cells: a) nucleus; b) cytoplasm. 4. Stem cells. 5. Cells’ nuclei.
Specimen 4. Stratified squamous nonkeratinized epithelium (human cornea). Stained with haematoxylin and eosin. The epithelium of the cornea, demonstrated in specimen, is a typical example of stratified squamous epithelium. Note the highly cellular basal layer and the transformation through the large polygonal cells of the intermediate layers to the superficial squamous cells. Intercellular substance between cells is absence. The junction between epithelium and underlying connective tissue is regular, and, as it, all epithelia, blood vessels do not extend belong the basement membrane. Illustrate and indicate: 1. Basement membrane. 2. Stratum basale. 3. Stratum spinosum. 4. Layer of the squamous cells.
References:
MODULE IІ. General Histology. Content module 3. Histology of the general tissues. Practical class № 17. Duration of the practical class: 2 hours. Theme: Epithelial tissues: glandular epithelium. Professional Motivation: The epithelia are a diverse group of tissues, which, with rare exceptions, line all body surfaces, cavities and tubes. Epithelia thus function as interfaces between biological compartments. Epithelia interfaces are involved in a wide range of activities such as absorption, secretion and protection and all these major functions may be exhibited at a single epithelial surface. For example, the epithelial lining of the small intestine is primarily involved in absorption of the products of digestion, but the epithelium also protects itself from noxious intestinal contents by the secretion of a surface coating of mucus. Epithelial tissues have morphofunctional features, which may be changed, in some pathologic states, for example inflammation, dystrophia, dysplasia and metaplasia. ^
Students’ Independent Study Program: I. Objectives for Students’ Independent Studies You should prepare for the practical class using the existing textbooks and lectures. Special attention should be paid to the following:
Real – life situations to be solved:
Visual Aids and Material Tools: Students should be able to indicate elements in the electron micrographs: 1. Exocrine cell. 2. Endocrine cell. Students’ Practical Activities: Students must know and illustrate a diagram: Diagram 1. Structure of the exocrine glands. Exocrine glands are glands which discharge their secretory product via a duct onto an epithelial surface. They may be divided into simple and compound glands. Simple glands are defined as those with a single, unbranched duct. The secretory portions of simple glands have two main forms, tubular or alveolar (acinar), which may be coiled and/or branched. Compound glands have a branched duct system and their secretory portions have similar morphological forms to those of the simple. Illustrate and indicate:1. Simple nonbranched tubular gland. 2. Simple nonbranched tubular gland with excretory portion looks like glomerulus. 3. Simple branched tubular gland. 4. Compound branched tubular gland. 5. Simple nonbranched alveolar gland. 6. Simple branched alveolar gland. 7. Compound branched alveolar gland. 8. Compound branched alveolar-tubular gland.
References:
MODULE IІ. General Histology. Content module 3. Histology of the general tissues. Practical class № 18. Duration of the practical class: 2 hours. Theme: Blood: erythrocytes, thrombocytes. Professional Motivation: Each system of the human body plays an important role in maintaining homeostasis in the internal cellular environment, but the movement of blood through the circulatory system is of fundamental importance. Although blood as a whole normally does not leave the vessels in which it is contained (with the exception of the menstrual function in females), nevertheless, it provides an efficient pick up and delivery service for cells in every organ of the body. Blood functions principally as a vehicle for the transport of gases, nutrients, metabolic waste products, cells and hormones throughout the body. Thus any sample of blood is composed not only of cells and molecules involved in transport processes but also cells and molecules in the process of being transported. ^
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