BMS 3002 Cellular Pathology - City University of Hong Kong PDF

City University of Hong Kong Department of Biomedical Sciences BMS 3002 Cellular Pathology 20 Sep 2023  Topics 1. Cell 2. Epithelia 3. Gland 4. Connective Tissues 5. Cartilage & Bone 6. Muscle 7. Circulatory System 8. Lymphoid Tissue 9. Gastrointestinal Tract 1...

City University of Hong Kong Department of Biomedical Sciences BMS 3002 Cellular Pathology 20 Sep 2023  Topics 1. Cell 2. Epithelia 3. Gland 4. Connective Tissues 5. Cartilage & Bone 6. Muscle 7. Circulatory System 8. Lymphoid Tissue 9. Gastrointestinal Tract 10. Endocrine System  Circulatory System 1. Heart pumps the blood 2. Arteries which carry 4. Veins which carry blood under high blood back to heart pressure and regulate under low pressure. flow through a given tissue or organ 3. Capillaries which permit interchange of metabolites between blood and tissues, 1. Tunica intima (inner layer) 2. Tunica media 3. Tunica adventitia (outer layer)  Arteries 1. Tunica intima (inner layer) Innermost layer that lines the lumen & single layer of endothelial cells 5-41  Arteries 2. Tunica media the middle layer containing varying amounts of smooth muscles, collagen and elastic fibres. 6-41  Arteries 3. Tunica adventitia (outer layer) the outermost, mainly collagenous vascular connective tissue layer Merges with surrounding neighboring tissue 7-41 Classification of Artery Aorta  Large/elastic arteries - Aorta Tunica Intima (inner layer) ~ composed of simple squamous (single layer of flat) endothelia cells, which form a smooth lining inside the blood vessel. Tunica media – 50-60 circular/ring with holes elastic sheet (stained black) https://www.lecturio.com/concepts/arteries/ ~ composed of smooth muscle cells and elastic fibers. adventitia media Tunica adventitia – composed of connective tissue that provides support and protection to the blood vessel , – contains collagen fibers which give strength and elasticity to the aorta. intima  Elastic arteries - Aorta Tunica Tunica Tunica Intima Media Adventitia Wheater’s Functional Histology, A Text & Colour Atlas p.144 Fig. 8.7 The artery system  Muscular artery Muscular arteries have the same basic structure as elastic arteries, but the elastic tissue is reduced Aorta VS https://www.lecturio.com/concepts/arteries/  Muscular artery e.g. femoral Tunica Intima a layer of endothelial cells, the innermost layer appears scalloped shape Tunica media arranged by 25-40 layers smooth muscle fibres, elastic fibres and collagen fibers Tunica adventitia Outermost layer of a muscular artery Composed of connective tissue that provides support and protection https://www.lecturio.com/concepts/arteries/ Muscular artery Wheater’s Functional Histology, A Text & Colour Atlas p.144 Fig. 8.8 Aorta vs. Muscular Artery  Arterioles – Small group artery Muscular arteries have the same basic structure as elastic arteries, but the elastic tissue is reduced https://www.lecturio.com/concepts/arteries/  Arterioles – Small group artery Tunica Intima Consists of endothelium with a very thin flattened endothelial cell ( E ) Tunica media ( M ) have 1 to 5 layers of smooth muscle fibres Tunica adventitia the collagenous fibres (indistinguishable) merges with surrounding supporting tissue Wheater’s Functional Histology, A https://www.lecturio.com/concepts/arteries/ Text & Colour Atlas p.145 Fig. 8.10 The microcirculation Type of Capillaries https://ohiostate.pressbooks.pub/vethisto/chapter/6-capillaries-and-sinusoids/  Capillaries ~ very small, average diameter of 7-9um – when cut transversely only 1 or 2 endothelial cells are normal visible ~ nuclei of endothelial cells are bulged into the lumen of capillary Wheater’s Functional Histology, A Text & Colour Atlas p.149 Fig. 8.15  Capillaries Capillaries are small, thin-walled blood vessels that are responsible for the exchange of nutrients, gases, and waste products between the blood and tissues in the body. They are an important part of the circulatory system and play a crucial role in maintaining the health and function of tissues and organs.  Capillaries 1.Size and shape: Capillaries are the smallest blood vessels in the body, with a diameter ranging from 5-10 micrometers. They are also very thin-walled, consisting of a single layer of endothelial cells. 2.Permeability: Capillaries are highly permeable, allowing for the exchange of nutrients, gases, and waste products between the blood and tissues. This is facilitated by small gaps between the endothelial cells, which allow for the passage of molecules and fluids. 3.Overall, capillaries are a vital component of the circulatory system, and their unique features allow for efficient exchange of materials between the blood and tissues. Understanding these features is important for students of histology, The venous system From : www.studyblue.com  Veins General features All veins have same basic structure compare with artery Weaker walls which tend to collapse when their lumens are empty In histological section, they (CV) have a more irregular profile than arteries (A) of corresponding https://www.lecturio.com/concepts/veins/ Wheater’s Functional Histology, A Text & Colour Atlas p.149 Fig. 8.16 Classification of Vein  Venules Tunica Intima – consist of flattened endothelium & a sparse connective tissue elements Tunica media ~ contains 1 to 3 layers of smooth muscle cells Tunica adventitia ~ mainly collagenous layer Wheater’s Functional Histology, A Text & Colour Atlas p.149 Fig. 8.16 https://www.lecturio.com/concepts/veins/  Venules Wheater’s Functional Histology, A Text & Colour Atlas p.151 Fig. 8.21  Medium veins General features ~ lumen of the vein is larger & more irregular the corresponding artery ~ its luminal surface is smooth instead of scalloped Tunica Intima – consists of little endothelial lining Tunica media ~ two or more layer of circularly arranged smooth muscle fibres can be found Wheater’s Functional Histology, A Text & Colour Atlas p.151 Fig. 8.19 Tunica adventitia ~ composed of collagen fibres which merge with surrounding tissue https://www.lecturio.com/concepts/veins/ Tunica Intima Large veins – thin layer of endothelial cells supported the endothelial connective tissue Tunica media ~ poorly developed ~ it is rather thin, consists mainly of collagenous fibres & litter smooth muscle Tunica adventitia ~ about twice as thick as the tunica media, ~ presence of smooth muscle in a stroma of collagenous and elastic fibres  Topics 1. Cell 2. Epithelia 3. Gland 4. Connective Tissues 5. Cartilage & Bone 6. Muscle 7. Circulatory System 8. Lymphoid Tissue 9. Gastrointestinal Tract 10. Endocrine System Lymphocyte https://www.sciencephoto.com/media/947016/view/lymphocyte-tem Lymphocyte in tissue From : Histology : a text and atlas : with correlated cell and molecular biology Lymphocyte in blood smear 2nd common white blood cell in blood circulation www.dreamstime.com/lymphocyte-cell-blood-smear  Lymphocyte in histological section, all lymphocytes look much same round and have strongly basophilic (dark blue) nucleus unobvious of pale staining cytoplasm, narrow rim surrounds the nucleus  new formed “lymphocytes” are constantly leave from the bone marrow to be distribute via the blood. but lymphocytes need enter the second type of lymphoid tissue (haemopoietic tissue), for further “immunological education” and contribute other important immune response. Central Lymphoid Tissue Peripheral Lymphoid Tissue (School) (Police Station)  Central Lymphoid Tissue (Thymus) are the sites where lymphocytes differentiate & develop the ability to recognize foreign antigens & distinguish nonself from self Thymus (T-lymphocytes à functional antigen presenting cell)  Thymus The newly form T-cell emerging from the bone marrow are immature & not yet capable of responding to an antigen. They are carried by blood to thymus for their “immunological education”. The mature lymphocyte re-enter the bloodstream and are distributed to other lymphoid tissues. From : http://course1.winona.edu  Thymus Fibrous capsule (Connective tissue?) surround the thymus Thin septa of fibrous tissue divide the organ incompletely into lobules each lobule composed of cortex & medulla cortex packed with large number of lymphocyte From : http://medcell.med.yale.edu/histology/immune_system_lab/thy mus.php (darker) The center of lobule is medulla (paler) https://vmicro.iusm.iu.edu/hs_vm/docs/lab7_2b.htm From : Histology : a text and atlas : with correlated cell and molecular biology  Lobule In histology, a lobule refers to a distinct, small subdivision or compartment within tissue. It is a structural unit that is often visible when examining tissues under a microscope. Under a microscope, lobules can be identified by their distinct boundaries and organization of cells. They are often surrounded by connective tissue, which helps provide support and structure to the lobule.  Cortex & Medulla Cortex: The cortex of the thymus is the outer region of the gland. It contains densely packed lymphocytes, which are specialized white blood cells involved in immune responses. From : Medulla: The medulla of the thymus is the http://medcell.med.yale.edu/histology/immune_system_lab/thy mus.php inner region, located deeper within the gland. It contains more loosely arranged lymphocytes and other specialized cells. The medulla is involved in the negative selection of T lymphocytes From : Histology : a text and atlas : with correlated cell and molecular biology Thymus high magnification From : diFiore’s Atlas of Histology  Thymus – medulla in medulla region presence of epithelial reticular cells, the cells having large pale stained nuclei, eosinophilic cytoplasm and prominent basement membranes From : From : diFiore’s Atlas of Histology https://vmicro.iusm.iu.edu/hs_vm/docs/lab7_2b.htm  Spleen– Function 1. Production of immunological responses against blood borne antigens 2. Removal of particulate matter and aged or defective blood cells, particularly erythrocytes  Spleen enclosed by a thick capsule of fibrous tissue that contain a few smooth muscle fibres mainly divide into two regions: red pulp & white pulp  Spleen Red pulp Red pulp of the spleen is named so because it appears reddish in color due to the presence of numerous red blood cells. Under a light microscope, the red pulp appears as a network of splenic sinusoids, which are elongated blood vessels lined with endothelial cells White pulp White pulp of the spleen is named so because it appears as small, spherical areas of white color. Under a light microscope, the white pulp is composed of clusters of lymphoid follicles. The lymphoid follicles contain germinal centers, which are regions where lymphocytes multiply and differentiate.  Spleen – filtering blood White pulp of the spleen is named so because it appears as small, spherical areas of white color. White pulp is composed of lymphoid follicles with germinal centres surrounded by lymphocytes The spleen is supported by trabeculae, which provide structural support. Connective tissue trabeculae carry the blood vessels into the spleen, provide internal support. Spleen – filtering blood From : Histology : a text and atlas : with correlated cell and molecular biology Spleen – filtering blood From : Histology : a text and atlas : with correlated cell and molecular biology Central Lymphoid Tissue Peripheral Lymphoid Tissue (School) (Police Station) Peripheral Lymphoid Tissue (Bodyguard Station) ~ are the sites where “T lymphocytes” & “B lymphocytes” encounter FOREIGN ANTIGENS and further the IMMUNE RESPONSE take place. e.g. Lymph node (filter the lymph) & spleen (monitor the erythrocytes)  Lymphoid Tissue Peripheral Lymphoid Tissue Encapsulate lymphoid Non-encapsulate lymphoid tissue tissue e.g. lymph node (filtering lymph) e.g. bronchi, e.g. spleen (filtering blood) e.g. ileum (peyer’s patches)  Peripheral encapsulate lymphoid tissue Lymph node 1. Non-specific filtration of non-self by phagocytic activity of macrophages 2. Aggregation, activation and proliferation of B & T lymphocytes From : diFiore’s Atlas of Histology  Lymph Nodes the node small, bean- shaped organs that play crucial role in immune system's function. appear as encapsulated structures with a distinct outer cortex and inner medulla From : diFiore’s Atlas of Histology Lymph Nodes – structure Capsule of collagenous fibrous tissue outer cortex, contains number of lymphoid nodules. contains densely packed lymphocytes the center of nodules is pale due to aggregate large lymphocyte cell with more cytoplasm & paler nuclei call germinal centers The central area is less lymphocyte and is known as the medulla the central area contains irregular cords & clumps of lymphoid cell call “medullary cord” From : Histology : a text and atlas : with correlated cell and molecular biology Lymph Nodes – structure From : Histology : a text and atlas : with correlated cell and molecular biology  Lymph Nodes – Cortex Encapsulated by dense collagenous fibrous tissue which trabeculae extend for variable distances into the substance of the node outer region is cortex, contains number of lymphoid nodules (LN) the center of nodules is pale paler due to aggregate large lymphocyte cell with paler nuclei call germinal centers (G) From : https://ar.pinterest.com/pin/357825132866737107/  Lymph Nodes – Medulla The central area is less cellular and is known as the medulla the central area contains irregular cords & clumps of lymphocytes, plasma cells & macrophages call “medullary cord (MC)” From : Histology : a text and atlas : with correlated cell and molecular biology  Lymph Nodes –filtering lymph ~ this technique (silver staining method) show the fine reticular architecture of the lymph node, reticulin fibres are stained blackish-brown  Peripheral Lymphoid Tissue Non- Encapsulate lymphoid tissue refers to clusters of lymphoid cell such as lymphocyte found throughout the body that are not enclosed by a distinct capsule. One prominent example of non-encapsulated lymphoid tissue is Peyer's patches, located in the mucosa of the small intestine.  Peripheral Lymphoid Tissue Non- Encapsulate lymphoid tissue lymphoid tissue (Digestive sys.) e.g. lymphoid tissue in mucosa of the digestive tract such as Peyer patches (group of lymphoid follicle) lymphoid in ileum (small intestine) lymphoid tissue (Respiratory sys.) e.g. lymphoid tissue in mucosa of the respiratory tract, such as lymphatic tissue in bronchi, bronchioles  Non- Encapsulate lymphoid tissue (Peyer’s patches.) peyer’s patches a small lymphoid aggregation in the wall of small intestinal lumen, colon or appendix play a role in immune defense Lymphoid aggregation are found scattered in the mucosa where they bulge dome-like into the lumen Each follicle contains various types of immune cells, including B-cells, T-cells, and specialized antigen-presenting cells called dendritic cells. These immune cells work together to detect and respond to pathogens and antigens encountered in the intestine. Lymphoid follicle Colon Appendix  Thymus Location: The thymus is a lymphoid organ located in the area between the lungs. Structure: The thymus is divided into lobules, which are composed of a central medulla and an outer cortex. The cortex contains densely packed lymphocytes, while the medulla contains fewer lymphocytes and more epithelial cells. Lymphocytes: The thymus is primarily composed of T lymphocytes, which develop and mature within the organ. Epithelial cells: The thymus contains a variety of epithelial cells, including thymic epithelial cells (TECs) and Hassall's corpuscles. TECs provide are like the caretakers of the thymus. They help and support other cells called T-cells Function: The thymus plays a crucial role in the development and maturation of T cells, which are important for the immune response.  Thymus Lobular Structure: The thymus is composed of small lobes or lobules, which are separated by connective tissue called septa. Each lobe contains different cell types. Cortex and Medulla: The thymus has distinct regions called the cortex and medulla. The cortex is the outer region, while the medulla is the inner region. Epithelial Cells: The thymus contains two main types of cells—epithelial cells and lymphocytes. Epithelial cells are arranged in networks or sheets, forming a framework for the thymus. Hassall's Corpuscles: Hassall's corpuscles are unique structures found in the medulla of the thymus. They appear as concentric circles of flattened, keratinized epithelial cells. Blood Vessels: Blood vessels, including capillaries, arterioles, and venules, are present throughout the thymus. These vessels supply nutrients and oxygen to the cells. Connective Tissue: Connective tissue, composed of collagen and other fibers, surrounds and supports the different structures within the thymus.  Spleen Location: The spleen is located in the upper left quadrant of the abdomen, near the stomach. Structure: The spleen is a soft, spongy organ that is surrounded by a fibrous capsule. It is divided into two main regions: the red pulp and the white pulp. Red pulp: The red pulp makes up the majority of the spleen and is responsible for filtering and removing old or damaged red blood cells from circulation. It contains sinusoids, which are large, open blood vessels that allow blood cells to pass through and interact with immune cells.  Spleen White pulp: The white pulp is located around the central artery of the spleen and is responsible for initiating immune responses. It contains lymphoid tissue, including T cells, B cells, and macrophages, which work together to identify and eliminate pathogens. Blood supply: The spleen receives blood from the splenic artery, which branches into smaller arterioles that enter the white pulp. Blood then flows into the red pulp, where it is filtered by macrophages and sinusoids before being returned to circulation via the splenic vein  Lymph node Location: Lymph nodes are small, oval-shaped organs located throughout the body, often found in clusters near major blood vessels and lymphatic vessels. Structure: Lymph nodes are surrounded by a fibrous capsule and are divided into compartments called lymphoid follicles, which contain immune cells and are separated by trabeculae. Cortex: The outer portion of the lymph node is called the cortex and contains densely packed lymphoid follicles, which are composed of B cells, follicular dendritic cells, and macrophages that work together to initiate immune responses.  Lymph node Paracortex: The paracortex is a region located between the lymphoid follicles and contains T cells, dendritic cells, and high endothelial venules that are important for activating T cell responses. Medulla: The inner portion of the lymph node is called the medulla and contains loosely packed lymphoid tissue, including plasma cells, macrophages, and medullary cords, which are composed of B cells and plasma cells. Afferent and efferent lymphatic vessels: Lymph enters the lymph node via afferent lymphatic vessels and is filtered through the lymphoid tissue before exiting via efferent lymphatic vessels. Blood supply: Lymph nodes receive blood from small arteries called arterioles, which branch into capillaries that supply the lymphoid tissue. Blood then drains into small veins called venules, which exit the node via the hilum.  Peripheral Lymphoid Tissue Location: Non-encapsulated lymphoid tissue is found in various locations throughout the body, including the respiratory tract, gastrointestinal tract Structure: Non-encapsulated lymphoid tissue is not surrounded by a fibrous capsule and is instead dispersed throughout the underlying tissue. Bronchus-associated lymphoid tissue (BALT): BALT is a type of MALT that is found in the respiratory tract and is important for initiating immune responses to inhaled pathogens.  Peripheral Lymphoid Tissue Gut-associated lymphoid tissue (GALT): GALT is another type of MALT that is found in the digestive tract and is important for initiating immune responses to ingested pathogens. It includes Peyer's patches, which are clusters of lymphoid follicles located in the small intestine. When stained with H&E (hematoxylin and eosin), lymphoid tissue appears as a mixture of darkly stained lymphocytes The H&E staining helps to highlight the cellular and structural features of the tissue, including the size, shape, and arrangement of the cells  Topics 1. Cell 2. Epithelia 3. Glands 4. Connective Tissues 5. Cartilage & Bone 6. Muscle 7. Circulatory System 8. Lymphoid Tissue 9. Gastrointestinal Tract 10. Endocrine System THE DIGESTIVE SYSTEM THE DIGESTIVE SYSTEM THE DIGESTIVE SYSTEM Gastrointestinal tract From : diFiore’s Atlas of Histology Gastrointestinal tract  Components of the walls of gastrointestinal tract Mucosa ~ lining epithelium ~ Lamina propria - a loose connective tissue ~ Muscularis mucosa - smooth muscle Submucosa ~ loose connective tissue - blood, lymph vessels & glands ~ submucosa nerve plexus Muscularis Externa ~ a thick layer of smooth muscle which arrange inner circular & outer longitudinal layer Adventitia ~ consist a thin layer of connective tissue. From : diFiore’s Atlas of Histology Mucosa ~ lining epithelium ~ Lamina propria - a loose connective tissue ~ Muscularis mucosa - smooth muscle Submucosa ~ loose connective tissue - blood, lymph vessels & glands Muscularis Externa ~ a thick layer of smooth muscle which arrange inner circular & outer longitudinal layer Adventitia ~ consist a thin layer of connective tissue. From : diFiore’s Atlas of Histology Esophagus  Esophagus Mucosa lined by stratified squamous nonkeratinized epithelium lamina propria & muscularis mucosae : consist a layer of loose connective tissue & discontinuous, a layer of smooth muscle Submucosa composed of loosely collagenous fibers, blood vessels & secreting glands Muscularis externa mainly is composed of skeletal (upper region) & smooth muscle Adventitia composed of loose connective tissue which blinds the esophagus to surrounding From : structure http://medcell.med.yale.edu/histology/gi_tract_lab/esophagus.php Gastrointestinal - Esophagus From : diFiore’s Atlas of Histology Gastrointestinal - Esophagus From : Histology : a text and atlas : with correlated cell and molecular biology Gastrointestinal - Esophagus From : Histology : a text and atlas : with correlated cell and molecular biology  Stomach From : Histology : a text and atlas : with correlated cell and molecular biology  Stomach Mucosa The mucosa of the stomach is lined with a simple columnar epithelium composed of mucous cells, chief cells, and parietal cells. Gastric pits are invaginations of the mucosa that lead to gastric glands, which secrete digestive enzymes and hydrochloric acid. Surface mucous cells and mucous neck cells secrete mucus to protect the stomach lining from acid and digestive enzymes. Submucosa consists of coarse, loosely connective tissue with large blood vessels Muscularis Externa composed of thick muscles layers (inner oblique, middle circular & outer longitudinal Serosa a thin layer of loose connective tissue From : Histology : a text and atlas : with correlated cell and molecular biology From : diFiore’s Atlas of Histology Stomach From : Histology : a text and atlas : with correlated cell and molecular biology Stomach Gastric pits Gastric glands (neck region) Gastric glands (base region) From : Histology : a text and atlas : with correlated cell and molecular biology  Stomach Gastric gland ~ branched, tubular glands ~ three regions : neck, body & base ~ near the surface mucous cell is “Gastric Pit” From : Histology : a text and atlas : with correlated cell and molecular biology  Stomach Three types of gastric gland cell Mucous neck cell, Oxyntic cell & Chief ell Mucous neck cell - Interspersed among the parietal cells in the neck of gland Parietal cell - found along length of gland - triangular in shape - large with strongly eosinophilic cytoplasm Chief cell - locate at the base - small than the parietal cells - vacuolate & strongly basophilic cytoplasm From : Histology : a text and atlas : with correlated cell and molecular biology Stomach gastric gland (base region) Parietal cells round to triangular shaped with large centrally-located nuclei, deeply eosinophilic cytoplasm Chief cells smaller than parietal cell, have a basally-located nucleus, Extensive , granular basophilic cytoplasm From : Histology : a text and atlas : with correlated cell and molecular biology  Small intestine Mucosa The mucosa of the small intestine is lined with a simple columnar epithelium Villi, finger-like projections, increase the surface area for nutrient absorption. Goblet cells are scattered among the absorptive cells, secreting mucus for lubrication and protection Submucosa consists of coarse, loosely connective tissue with large blood vessels Muscularis Externa composed of thick muscles layers (inner circular & outer longitudinal From : Histology : a text and atlas : with correlated cell and molecular biology Serosa is composed of mesothelium, a simple squamous epithelium From : diFiore’s Atlas of Histology  Small intestine From : Histology : a text and atlas : with correlated cell and molecular biology  Small intestine Surface absorptive cell -many villi covered by a single layer of columar cell Goblet cell -Balloon shaped apical cytoplasm Paneth cell Locate at the bottom pyramidal shape eosinophilic granules in cytoplasm From : Histology : a text and atlas : with From Gartner LP, HIATT JL, Color Textbook of correlated cell and molecular biology Histology, 3rd ed. Philadelphia, 2007, p 399.  Large intestine Mucosa - The mucosa of the large intestine is lined with a simple tall columnar epithelium. - Unlike the small intestine, the large intestine does not possess villi. - It contains numerous long, straight tubular intestinal glands that are characterized by the presence of many goblet cells, which secrete mucus to lubricate the passage of fecal material. Submucosa - The submucosa of the large intestine is composed of dense irregular connective tissue that houses blood vessels, providing support and nourishment to the mucosal layer. Muscularis Externa - The muscularis externa of the large intestine consists of two layers: an inner circular layer and an outer longitudinal layer. These muscle layers facilitate the movement and mixing of fecal material through peristaltic contractions. Serosa The outermost layer of the large intestine, the serosa, is composed of mesothelium, a type of simple squamous epithelium. It serves to protect and support the large intestine, aiding in its movement within the abdominal cavity. From : https://www.histology- world.com/keyfeatures/largeintestine1.htm  Large intestine Muscularis Externa ~ composed of two layers of THICK smooth muscles (inner circular & outer longitudinal) Serosa ~ a thin layer of loose connective tissue From : Histology : a text and atlas : with correlated cell and molecular biology  Stomach Small Intestine Large Intestine - Simple columnar - Simple columnar - Simple tall columnar epithelium with Mucosa mucous, chief, and epithelium with villi and epithelium with no villi, goblet cells numerous goblet cells parietal cells - Contains blood vessels, - Contains connective - Dense irregular Submucosa lymphatics, and nerves tissue, blood vessels, connective tissue for support and lymphatics containing blood vessels - Three layers of smooth - Two layers: inner - Inner circular and outer Muscularis muscle: oblique, circular, outer longitudinal muscle Externa circular, longitudinal longitudinal layers - Composed of - Composed of - Composed of Serosa mesothelium (simple mesothelium (simple mesothelium (simple squamous epithelium) squamous epithelium) squamous epithelium) Alimentary canal  Liver From : https://www.health.com/condition/hepatitis-c/what-causes-cirrhosis-liver Liver Capsule layer The liver is surrounded by a connective tissue capsule call Capsule of Glisson Liver lobules The liver is organized into functional units called hepatic lobules. Each lobule is hexagonal in shape and consists of plates of hepatocytes radiating outward from a central vein. From From https://www.researchgate.net/figure/Group-C-a-Glissons-capsule- http://www.vivo.colostate.edu/hbooks/pathphys/digestion/liver/histo_lobule.html thick-arrows-central-vein-Cv-portal-area-thin_fig1_324808000  Liver Hepatocytes Hepatocytes are the main functional cells of the liver. These polygonal cells have abundant cytoplasm, centrally located round nuclei, and prominent nucleoli. From https://www.researchgate.net/figure/Group-C-a-Glissons- capsule-thick-arrows-central-vein-Cv-portal-area-thin_fig1_324808000 https://embryology.med.unsw.edu.au/embryology/index.php?title= File:Liver_histology_004.jpg&mobileaction=toggle_view_mobile  Liver Sinusoids Sinusoids are specialized capillaries located between the plates of hepatocytes. They are lined by fenestrated endothelial cells and Kupffer cells (macrophages) that help filter and process blood from the hepatic portal vein and hepatic artery. From https://sketchfab.com/3d-models/microscopic-anatomy-of-the-liver-cf557146364e49dea18f70e04343f200  Liver Portal area Portal triads are located at the corners of hepatic lobules and consist of branches of the hepatic artery, portal vein, and bile duct. Connective Tissue The liver is supported by connective tissue containing blood vessels, lymphatics, and nerves that supply and maintain the structural integrity of the organ. From http://www.siumed.edu/~dking2/erg/GI162b.htm From https://www.researchgate.net/figure/Group-C-a- Glissons-capsule-thick-arrows-central-vein-Cv-portal- area-thin_fig1_324808000  Topics 1. Cell 2. Epithelia 3. Gland 4. Connective Tissues 5. Cartilage & Bone 6. Muscle 7. Circulatory System 8. Lymphoid Tissue 9. Gastrointestinal Tract 10. Endocrine System Endocrine System Endocrine System Consists of cells, tissues & organs à Hormones Cell in tissues are arrange in cords & clump Surrounded by extensive capillary network Hormones enter bloodstream & interact with target organs with specific receptor From : diFiore’s Atlas of Histology 11th edition Eroschenko Pituitary Glands Pituitary Glands A small, slightly elongated organ, ~ 1 cm diameter Lying in a bony cavity in the floor of the skull Divided to anterior pituitary and posterior pituitary Rich vascular network form a fenestrated capillary plexus Three major histology areas 1. Pars distalis 2. Pars intermedia 3. Pars nervosa From : diFiore’s Atlas of Histology 11th edition Eroschenko Pituitary Glands (Three major histology subdivisions) 1. Pars distalis Cell arranged in clumps between the clumps are seen capillaries, blood vessels & thin connective tissue fibers that separate the clumps Pituitary Glands (Pars distalis – 3 major cells) Chromophobes ~ Pale nuclei & cytoplasm with poorly defined cell outlines Acidophils (alpha cells) ~ Are more numerous & red-staining granules in cytoplasm and blue nuclei Basophils (beta cells) ~ Less numerous & blue-staining granules and darker-staining cytoplasm From : http://medcell.med.yale.edu/systems_cell_biology/endocrine_systems_l ab.php Pituitary Glands (Pars intermedia) Contains follicles and colloid-filled cystic follicles Pituitary Glands (Pars nervosa) Contains unmyelinated axons and supportive pituicytes with oval nuclei Thyroid Glands located in the anterior of neck Single gland consists of large right & left lobes Arrange in clumps & store secretory products within cytoplasm From : diFiore’s Atlas of Histology 11th edition Eroschenko Thyroid Glands (general view) Consists of follicles which are spherical bodies of variable size. Each follicle is made up of a simple epithelium enclosing some acidophilic “colloid substances” Epithelial cell are normally cuboidal in shape, variations from squamous to columnar in shape indicate an underactive or overactive state. Connective tissue septa divide the glands into lobules and numerous blood vessels Parathyroid Glands Small oval glands are embedded in thyroid gland but separated by thin connective capsule Nodular configuration Composed of two cell types, known as chief & oxyphil cell Parathyroid Glands Chief (principal) cells ~ are most numerous cells ~appear round & have a pale with slightly acidophilic cytoplasm Oxyphil cell ~ are larger & less numerous than chief cell ~ acidophilic cytoplasm with dark nuclei ~ find as single cells or in small clumps throughout the gland From : https://en.wikipedia.org/wiki/Parathyroid_chief_cell#/media/File:Parathy roid_oxyphil_and_chief_cells_-_annotated.jpg Adrenal Glands Near superior pole of each kidney Surround by dense irregular connective tissue & embedded in the adipose tissue around the kidney Arrange in clumps & store secretory products within cytoplasm Consists of an outer cortex (adrenal cortex) & inner medulla (adrenal medulla) Adrenal cortex further divided into 3 zones, zone glomerulosa, zone fasciculata & zone reticularis Adrenal Cortex Adrenal Gland Adrenal Cortex Zone glomerulosa thin zone inferior to the adrenal gland capsule. arranged into ovoid groups or clump small clumps Surrounded by numerous sinusoidal capillaries Cytoplasm of these cell stains pink Adrenal Cortex Zone fasciculate intermediate and the thickest zone. Arranged in vertical column Lipid droplets in cytoplasm sinusoidal capillaries between the cell column follow a vertical Adrenal Cortex Zone reticularis innermost zone that is adjacent to the adrenal medulla Form anastomosing cords surrounded by sinusoidal capillaries  Adrenal Glands – Adrenal Medulla General structure: The Adrenal Medulla is the inner layer of the Adrenal Glands and is composed of chromaffin cells. Chromaffin cells: These are specialized cells. These large, polygonal cells have abundant cytoplasm and contain dark-staining granules. Blood vessels: Both of Adrenal Cortex and Adrenal Medulla is also highly vascularized, with numerous blood vessels running through it.