Histology 1st year medschool


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A presentation summarising the key features of the main tissues for 1st year medical school histology.

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Histology 1st year medschool

  1. 1. Histology1st year medical school Cambridge University by Christiane Riedinger 2011
  2. 2. Aim of this presentation When starting to learn histology, I was looking for simple overviews presenting the key features of each tissue type or tissue found in the body. Since I could not find that anywhere, I made it myself! This presentation should be used with a standard histology textbook (or the internet ;-)) showing you slides/pictures of the structures described here. Pictures of particular stains (part I) have been cited.C.Riedinger
  3. 3. Contents 1. staining and fixing techniques 2. histological properties of human tissue types 2.1. connective tissue 2.2. muscle tissue 2.3. nervous tissue 2.4. epithelial tissue 3. histological properties of anatomical structures 4. ways to identify tissues/cells • blood cells (connective tissue) • ganglia (nervous tissue) • components of the urinary systemC.Riedinger • tissue types of the GI tract
  4. 4. 1. staining and fixing techniquesC.Riedinger
  5. 5. 1. staining and fixing techniques (2)C.Riedinger
  6. 6. 1. staining and fixing techniques (3)C.Riedinger
  7. 7. 1. staining and fixing techniques (4)C.Riedinger
  8. 8. 2. tissue types: connective tissue Overview of tissue types: C.Riedinger tissue layers/comp function cell types appearance stains type onents - binds - fibroblasts - collagen types: - massons trichrome functional cell (excrete ECM), mostly I, II in 1. Loose (10-20% C) (collagen) - groupings come from cartilage, II in 2. Dense (40-50% C, van gieson (collagen) together mesoderm skin, vessels, IV in tendons 90%) - elastin stain (elastin) - regulation - adipocytes epithelium of 3. elastic - eosin (collagen, but not - chondroblasts basement lung, skin, bladder, specific) - myofibroblasts membranes vessels, - silver stain (reticulin) - immune cells: - elastic fibres change with age macrophages, (stain poorly) 4. cartilage histiocytes, mast - ground 70% ground cells, white blood substance substance cells (= gel embedding 5. bone collagen and = cartilage with 70% elastin) salts connec- 6. fat tive white or brown 7. blood (mesoderm)C.Riedinger
  9. 9. 2. tissue types: muscle tissue Overview of tissue types: C.Riedinger tissue layers/comp function cell types appearance stains type onents - no striations, spindles - massons trichrome: - 1 elongated centrally located nucleus (muscle, connective - irregularly branching tissue) fasciculi, can have ganglia - shorter, often layered - unicellular: - fasciculi arent in parallel - surrounded by myoepithelial cells - no myofibrils lamina (secretory glands), - caveolae - attached via link - gap junctions pericytes (like proteins smooth muscle, - endomysium: - intermediate surrounds blood - appears striated supp. tissue around vessels, called - 1-2 central nuclei each individual multiunit smooth - intracellular boundaries hard muscle fibre to see - contraction muscle as each unit muscular functions - perimysium: - cells appear continuous (funct. Syncytium) (embryologically a surrounds each individually), - branched ends subtype of muscle cell bundle myofibroblasts - long, cylindrical connective from = fascicle - rich capillary network (contractile and mesoderm) - epimysium: - intercalated discs (Z) collagen, scarring) around groups of - gap junctions - no end plates, tendons! fasciculi, dense - multicellular: - diad (SR + T) collagenous sheeth smooth (lots of around whole cells function as - extremely elongated muscle single unit), - multinucleate (in transverse section may not cardiac, skeletal be seen) - nucleus at periphery - striated - parallel fasciculi - triad = SR terminal cisterna + T-tubuleC.Riedinger
  10. 10. 2. tissue types: muscle tissue (2) C.Riedinger striated: light: I-band containing Z-line (made of actin fibres) dark: A-band containing myosin fibres H-band: myosin-only region in A-band M-line: middle of A-band T-tubules: T-tubules are at level of Z-bands (cardiac, amphibian skeletal) T-tubule at junction of A and I bands (skeletal) Red skeletal muscle: (aerobic, stains more strongly) rich in myoglobin, numeruous mitochondria, many capillaries White skeletal muscle: (anaerobic, stain is more pale) less myoglobin, fewer mitochondria, poorer blood supply cardiac: junctions! intercalated discs: black line perpendicular to length of fibre, parallelt o striations membrane-to-membrane contact in intercalated discs (only visible at EM resultion): 1. Fascia adherens: intermediate junction, anchors actin at terminal sarcomeres - mechanical connection 2. desmosomes: (macular adherens), attachment of intermediate filaments to cytoskeleton - mechanical 3. Gap junctions: (nexus), exchange/transmission of ions and small molecules from cell to cell - electrical result: functional syncytium! purkjinje fibres: pacemaker cells, larger than cardiac muscle cells and sometimes binucleated contain lots of mitochondria but less myofibrils (irregular), no T-tubules and intercalated discs still have desmosomes and gap junctions, lots of glycogen (can stain for it specificlally!) smooth: dense bodies/plaques: points of attachment for actin filaments caveolae: invaginations of the plasma membrane, help Ca2+ entry macula - spot (latin)C.Riedinger
  11. 11. 2. tissue types: nervous tissueOverview of tissue types: C.Riedinger tissue layers/comp function cell types appearance stains type onents - electrically - neurons transverse: - large cell body - Nissl methylene blue conduct signals (multipolar, - bundles of axons (rER) bipolar, = fasciculi - large, round, pseudounipolar) prominent but pale - Sudan black (for LM) - glial cells - endoneurium = staining nucleus, and osmium (for EM) (schwann cells, around each nerve dispersed chromatin (myelin and lipids, oligodendrocyte, fibre along with connective dissue) astrocytes, myelin - extensive basophilic satellite cells) cytoplasm - fibrocytes - perineurium = dense conn. tiss - large and central around bundles of nucleolus nerve fibres = (transcriptional fascicles activity) nervous - epineurium = - in longitudinal (from ectoderm?) loose conn. tiss section of nerve around fascicles trunks: zig-zaggy lines with round nuclei Longitudinal: (of schwann cells!!!!) dendride, nodes of ranvier - abundant rER in other: ganglia, nucleus and dendrites myelin, axon (= Nissl substance hillock, terminal from Nissl staining RNA) - ganglia: cell bodies and/or synapses
  12. 12. 2. tissue types: epithelial tissue Overview of tissue types: C.Riedinger tissue layers/comp function cell types appearance stains type onents - cover the body - very closely simple: and line spaces packed epithelial = single layer and tubes within cells - squamous - flat thin cells it - subtype reflects difficult to distinguish sometimes only nuclei - protect function visible - absorb - goblet cells - secrete (mucus secreting) - cuboidal - round centrally located nucleus, often - skin, nephrons, - hair cell (sensory) polygonal airways, glands, - gustatory (taste gut... cell) - columnar - tall, elongated cells may be ciliated Even though not a - pseudostratified - mostly ciliated cells, nuclei not in line cell type: epithelial epithelial tissue always stratified: (endoderm, contains a basement = multiple layers ectoderm) membrane (lamina densa) - squamous - NEVER CILIATED! consisting of type (wear & tear) IV collagen - cuboidal - only top layer flat, bottom layer cuboid - columnar - transitional - intermediate betw. Stratified cuboidal and squamous. But all layers have the same shape!C.Riedinger
  13. 13. 3. anatomical structures: vessels organs: vessels C.Riedinger layers blood other vessels internal elastic external elastic 1. Tunica intima 2. Tunica media 3. Tunica adventitia lamina lamina 1a. Endothelium fenestrated - smooth muscle - supporting tissue: (1 flat layer, cells difficult layer of elastin - collagen collagen to distinguish in LM, often separating 1. - elastin less defined - contains innervation see only nuclei) and 2.. In very - quite thick compared to and blood supply (for layer of 1b. Basement large elastic intima very large vessels, vasa general elasting membrane vessels hard to vasorum) separating 2. 1c. Connective tissue see as media - in continuation with and 3. has so many surrounding tissue layers of elastin. + very broad, contains concentrically arranged arteries, + + layers of elastin with + + elastic some smooth muscle between layers, elastin decreases with age + arteries, circumferentially + + + + muscular arranged smooth muscle + + + arteriole + (almost entirely smooth - (merges with <0.3mm diam (thin) muscle) surrounding tissue) overall much + + thinner wall vein - + - (thin) (most prominent) compared to (thin) lumen lymph like veins but no erys in lumen, few leucocytes and precipitaed lymp protein (artifact of preparation!) continuous, fenestrated + (windows bridged by thincapillaries (only 1a and 1b) - - - - diaphragm) or sinusuidal with proper gaps venule + - - - +nuclei of endothelial cells are elongated in direction of vessel, smooth muscle nuclei are elongated circumferentially
  14. 14. 3. anatomical structures: respiratory systemorgans: respiratory system (lung) C.Riedinger 1. mucosa? compart- 2. submucosa 3. cartilage stain ment 1a. epithelium 1b. Lamina propria 1c. Smooth Muscle - numerous - C-shaped hyaline - H&E - pseudostratified seromucinous cartilage columnar ciliated - loose connective glands - with layers of - many mucus tissue fibroelastic tissue - serous cells staintrachea secreting goblet - - many blood between cart. rings cells strongly vessels - submucosa - unusually thick - mucous cells stain poorly merges with its basement perichondrium - pseudostratified - fewer - flatter, columnar ciliated seromuceous glands interconnected (less tall, smaller) - more dense plates of cartilagebronchus - fewer goblet cells - more elastic + rather than rings - not C-shaped - simple columnar -seems to be there - ciliated - <1mm diam. -very thin - is it but much less - smaller bronchioles + glands and thinner thin-walled there?bronchioles pulmonary artery cuboidal prominent feature! - less to no goblet branches can lie cells, but Clara cells! next to bronchiole (= resp. bronchiole) - lined with pneumo- - alveolar ducts: smooth muscle cells, collagen and elastic fibres cyte type I cells (40% - alveolar septum (wall): alveolar capillaries and sparse network of elastin and collagen covering 90%) with pneumocytes of the walls of the two adjacent alveoli next to it - can only see nuclei - 60/10% pneumocyte - septum also contains few fibroblastsalveoli type II (cuboidal, much - elastin and collagen condense around alveolar openings to form supporting network CP, secrete surfactant) for lung parenchyma (parenchyme = bulk of a substance = lung material) - endothelial cell on the - 8um openings in septum: alveolar pores (of Kohn) for air exachange blood side - also alveolar macrophages (dust cells) with thin flattened, even nucleus
  15. 15. 3. anatomical structures: urinary system organs: urinary system (kidneys) C.Riedingercompartment epithelium other cells features (Wheaters p. 318, 320,325) simple squamous endothelium 1. juxtaglomerular afferent arteriole - modified smooth muscle cells cells simple squamous endothelium - podocytes - 1* and 2* foot processes (fenestrated) - mesangial cells - embrace capillary loops - filtration barrier: 1. Endothelial cells, 2. Basement 2. extraglomerular membrane, 3. podocytes mesangial cells - contractive cells, phagocytotic (can reduce GFR) glomerulus JUXTAGLOMERULAR APPARATUS - surround glomerular capillariesrenal formed by comparments of - mesangium = supportive tissue similar to basementcorpuscle glomerulus, afferent arteriole and membrane, cytoplasm very stained - flat, elongated continuous with glomerular mesang. cells distal convoluted tubule - conical mass, cytoplasmic processes simple squamous epithelium - invaginated sphere bowmans - - visceral and parietal layer capsule (but where is visceral layer? Cant see it on EM) simple cuboidal epithelium - brush border (aids reabsorbtion)proximal convoluted tubule - - many mitochondria, endocytotic vesicles and(PCT) lysosomes - FUZZY LUMEN!!!thin descending and thin simple squamous epithelium -ascending loop of henlethick ascending loop of simple cuboidal epithelium (low) -henle 3. macula densa - NO brush border! simple cuboidal epithelium - smaller cells, stain less intensely - CLEAR LUMEN!!! (where in contact with - nucleus protrudes into lumendistal convoluted tubule glomerulus) - cell volume smaller(DCT) - specialised epithelial cells - closely packed, taller, thin basement membrane - located on side of DCT that faces corpuscle simple cuboidal epithelium - wider than CDTcollecting tubules (CT) - - less regular in shape simple columnar epithelium - principal cells - large diameter - pale cytoplasm, few organellescollecting duct (CD) - a-intercalated cells - pale stained - short microvilli - darker cytoplasm, many mitos, vesicles (H+) stratified transitional epithelium - 3-6 layersureter, bladder - - thick luminal surface - impermeable to urine/water
  16. 16. 3. anatomical structures: glands organs: glands C.Riedingertype of gland arrangement main component ducts features other acini (end pieces) = intercalated ducts clusters of mucus mucus secreting: bigger, sain pale lots of vessels, nerves, lobules separated by leading to striated secreting cells, serous with nuclei on side. Serous (parasympathetic) ganglions,Salivary septa, surrounded by ducts, stain red. secreting cells, or a mix of secreting: smaller, stain strongly, extretory ducts, connective capsule Simple cuboidal epi, both. Duct system more pyramidal/cuboidal cells tissue, lymphatic vessels central round nucleus prominent acini (exclusively serous intercalated ducts arranged circularly with abundant blood supply, network with central nuclei, (difficult to ID with lateral nuclei (apex towards of arterioles. in ducts: surrounded by fine LM), leading to inside, nucleus basal), tiny cells change from squamous or network of supporting intralobular and lobules separated by lumen, sometimes centroacinar cuboidal epithelium to stratified tissue containing interlobular ducts (big loose supporting tissue cells cuboidal in large ducts sinusoids) lumen) surrounded byPancreas collagenous capsule. immunological stain for glucagen Exocrine (80-85%) and smaller, scattered pale staining (alpha-cells, smaller) or insulin endocrine (1-2%) blobs of varying size, cells (beta-cells, stain with aldehyde features! islets of langerhans - contained smaller than acinar fuchsin) reveals that glucagon is cells, evenly distributed cells with produced in the periphery evenly distributed nuclei whereas insulin is produced centrally polyhedral cells with round nuclei, some binucleated, hepatocytes and sinusoid arranged into branching sheaths arterioles of 1 cell thickness, separated by sinusoids which appear as empty macrophages (Kupffer cells) spaces present in sinusoids to remove polygonal lobules with canaliculi with microvilli debris, sinusoids have gaps thin boundaries ofLiver that run countercurrent between endothelial cells to collagenous supporting portal tracts/triads: entry to the sinusoids promote exchange of plasma tissue site of blood from thin-walled veins, thicker walled components with the terminal branches of arteries, darkly staining bile hepatocytes (see EM). portal vein and hepatic ducts. Also contains lymphatic artery, leads to central tissue/ducts which is often vein, exit of bile duct collapsed (canaliculus).
  17. 17. 3. anatomical structures: glands (2) organs: glands C.Riedingertype of gland arrangement components products features other follicles, contain thyroid morphology ~ activity: resting hormones bound to hormones stored in tri-iodothyronine, 4- thyroid follicular cells flattened, thyroglobulin, a glycoprotein, homogenous colloids, iodothyronine lots of colloid, active thyroid when stored. Thyroid gland is lined with single layer of (=thyroxine) follicular cells large, columnar, unique in storing lots of hormone Thyroid lobulated cuboidal follicular cells basal nucleus, less colloid when inactive! scattered, lumps or single cells, endoneurocrine, derived from parafollicular cells calcitonin near fenestrated capillaries for neural crest cells? hormones to enter blood stream poorly defined lobules large, round nuclei, resting cells have chief/principal cells pale cytoplasm, prominent golgi, rER, + septa contained in PTH (most common) secretory granules. When active the capsule of thyroid glandular elements can be smaller, more rER, stain more strongly gland (septa [blue] = intermixed with adipose cells, in Parathyroid extensions of capsule age becomes infiltrated by containing eosinophilic cytoplasm, numerous lymphocytes neurovascular oxyphil cells (minor unknown mitochondria, larger than structures) component) principal cells glandular epithelium, intimate vascular cords or clumps of cells, sinusoid *50% somatrophs (GH) connections with capillaries, collagen and reticulinAnteroir 20% corcitutrophs (ACTH) hypothalamus. GH, ACTH, LH, FSH, network, chromophobes:pituitary blob 20% lactrotrophs (prolactin) chromophobe and prolactin, thyrotrophin smallest, few granules,(adeno) 5% gonadotrophs (LH, FSH) chromophil cells = chromophils: acidophil or 5% thyrotrophs (thyrotrophin) ~troph cells with lots of basophil. granules* axons: lots of granules, accumulate in distended terminations = Herring bodies,Posterior non-myelinated axons, connects to granules contain hormone cell bodies of axons inpituitary pituicytes (speciallised ADH, oxytocin hypothalamus via stalk precursors generated in cell body, hypothalamus(neuro) glial cells) final hormone generated during transport. Pituicyte EM: few granules
  18. 18. 3. anatomical structures: GI tract C.Riedinger
  19. 19. 4. identify: blood cells (connective tissue) BLOOD Wheaters: table page 64 1. red blood cells: - total absence of organelles - no nucleus - flattened disc with elevated circumference - reticulocytes (= precursors, <1% of circulating erys) have some residual nuclear material - very young cells some rER and mitochondria 2. white blood cells: (1/1000 blood cells) 5 types, named based on staining properties of granules granulocytes: Neutrophils do not stain in humans 60% eosinophils pick up eosin and therefore stain orange 3% basophils pick up azures and therefore stain blue, rarest cells 1% single multilobed nuclei (polymorphonuclear) originally believed to be polynuclear mononuclear leucocytes: lymphocytes clear cytoplasm, rounded nucleus 34% (agranular) monocytes large, indented curved nucleus 4% non-lobulated nuclei agranolucytes 3. platelets: - small - non-nucleated - round or oval, biconvex - cytoplasm purple stained - granules = 20% of platelet volume - many organellesC.Riedinger
  20. 20. 4. identify: blood cells (connective tissue) (2)C.Riedinger
  21. 21. 4. identify: type of ganglia (nervous tissue) C.Riedingerhow to distinguish gangliacell bodies are large with smaller supporting cells around itsymp + parasymp: contain synapses (stellar ganglion = largest symp ganglion)sensory: just contain cell bodiesappearancesensory ganglion: many and larger nuclei of satellite (supporting cells), form neat circle around cell body, even larger cell bodies pseudounipolar neurons!sympathetic ganglion: smaller and more scattered satellites, smaller cell bodies more space between cell bodies as axons and dendrites have to pass through! same basic structure as sensory gangliaparasymp. Ganglion: near target organ! Islands of connective tissue with blood vessels, nerves and ducts nerve cell bodies lie within nerve trunk, are surrounded by support cells, less satellites, smaller cell bodies large cell bodies and axonsnerves in longitudinal sectionzig-zaggy strands with nuclei of schwann cells visibleeach myelin producing schwann cell covers ca. 1mm of the nerve fibrein-between: nodes of ranvieroften stained black with pink connective tissue in-between individual myelinated fibres
  22. 22. 4. identify: GI tract - looks more structured than stomach C.Riedinorgans: alimentary system (gut) - mucin stains more blue than cyanWheaters: page 286, 287, for glands 97How to distinguish different parts of the gut:Are there villi? * Yes Small intestine: Duodenum/Jejunum/Ileum Are there brunners glands? * Yes Duodenum * No Jejunum/Ileum Are there peyers patches? * Yes Ileum * No Oesophagus/Stomach/Colon * No Jejunum Are there glands? * Yes Stomach/Colon What do the glands look like? Straight and beautiful Colon Thick very thick layer underneath ducts, less Stomach ordered * No Stratified squamout epithelium? Oesophagus
  23. 23. 4. identify: urinary system organs: urinary system (kidneys) C.Riedingeradrenal glandegulfed in dense supporting tissue that extends into gland to support secretory cells zona glomerulosa 5-10% secretes mineralocorticoids (e.g. aldosterone) whorls of cells and capillaries zona fasciculata 75% narrow cords of large cels sinusoid capillariescortex: rich in sER and lipids "foamy" secretes glucocorticoids (e.g. cortisol) zona reticulosa irregular network of branching cords numerous capillaries of wide diameter smaller cells than other two layers secretes androgenic steroidsmedulla: chromaffin cells clumps and cords of cells surrounded by fine supporting tissue large nucleus (stains blue) basophilic cytoplasm secretes catecholamines (e.g. (nor)adrenaline)steroid secreting cells: many mitochondria with unusual tubular cristae sER lipid droplets (if secreting cholesterol, in cortex) membrane-bound granules (if secreting catecholamines in medulla, but those are not steroids)
  24. 24. The End.