Download Human Tissues I

CLASS: 10:00-11:00
DATE:11-1-10
PROFESSOR: Dr. Cotlin
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Introduction to Human Tissues #1
Scribe: Eric Larson and Lauren Morris
Proof: Eric Larson and Lauren Morris
Page 1 of 6
Intro [S1]
a. So what we’ll do today, and over the next few lectures, is review the basic tissues
b. What I mean by that is: epithelial, connective, bone, nerve and so on
c. A lot of today will be spent on epithelial tissue
Histology [S2]
a. There are over 200 specialized types of cells in the body
b. Everything can be classified as cell, or non-cell (extracellular matrix – the environment our cells live in)
c. Of those cells, each can be classified as epithelial, muscle, connective, or nerve
Scale of Tissues, Cells and Molecules [S3]
a. This shows us the scale of images we’ll look at
b. Many of the images we’ll look at are light microscopy
c. We’ll be working at the range where we can see individual tissues and cells
Resolving Power [S4]
a. Animal cells are often between 10-20 microns
b. For this reason, it’s necessary to use microscopy to see them
Light Microscopy [S5]
a. Many types of light microscopy
b. We’ll often use bright field light microscopy
c. Fluorescence is where you use a fluorescent molecule to look for particular cells
d. Phase contrast is a way to look at variations in thickness and depth
e. Dark field is basically having a negative image
f. Polarizing is the difference of refractive index in two beams of light
Electron Microscopy [S6]
a. Transmission (EM) is electron the micrograph used most often
b. Instead of light, a beam of electrons is used
c. Scanning EM is where a beam of electron scans the coated surface of a specimen
d. Freeze fracture is where specimens are frozen, usually with liquid nitrogen, and cracked open
Types of Light Microscopy [S7]
a. Here we see examples basic bright-field, phase contrast, and dark-field (or negative image) microscopy
Comparison of Electron Microscopy Variations [S8]
a. On the left we see a nice scanning EM image
b. The entire structure is coated with an electron dense material and then scanned
c. Results in this nice, detailed image
Specimen Preparation [S9]
a. A few comments about specimen preparation: first we fix our tissue with formaldehyde to lock everything in
place
b. You next remove the water with increasing concentrations of alcohol to replace the water
c. Next, the specimen is embedded
d. You section the specimine with microtome
e. Finally, you can stain the specimen with various dyes
f. Hematoxylin and Eosin (HE) is most common
g. Hematoxylin is blue and stains acidic materials, Eosin is pink and stains basic materials
h. If you stained a cell with Hematoxylin and Eosin, what would the nucleus likely appear as?
i. Dark blue or purple because it is acidic and is stained by hematoxylin
i. PAS is a reaction that allows us to detect carbohydrates
Kidney Cells [S10]
a. You can see the individual cells here in this picture of a collecting duct
b. Stained with H and E stains, and so you can very clearly see the cell nuclei and cell borders
c. As a side note, when pictures like this are shown she’ll tell us where the tissues are found
i. At this point, we won’t need to tell her where in the body it is found, but she might ask us to tell her what
type of cell it is
Chicken FibroblastS11]
a. Picture of a chicken fibroblast
b. H and E can Stain practically any cell – chicken cell and the protozoa are both stained
Diagram of Intestine With Different Stains [S12]
a. A picture showing the epithelium of the GI tract
b. The bottom set of pictures shows the difference that various stains make
c. If you use a particular stain, you can highlight different structures
CLASS: 10:00-11:00
Scribe: Eric Larson and Lauren Morris
DATE:11-1-10
Proof: Eric Larson and Lauren Morris
PROFESSOR: Dr. Cotlin
Introduction to Human Tissues #1
Page 2 of 6
d. So depending on what you’re looking for you can pick a stain that will display the tissue well
XIII.
Intestinal Epithelium Stained by PAS [S13]
a. This is epithelium in the intestine stained with a Periodic Acid-Schiff (PAS)
b. You can see some nuclei, but not nearly as evident as with an HE stain
c. What we see here is the dark red/purple border along the edge of the cell because there are so many
glycosylated proteins in that area
XIV.
Direct and Indirect Immunocytochemistry [S14]
a. The last concept is immunocytochemistry: the use of antibodies
b. If we want to find a particular cell or tissue, we can use an antibody specific for the cell
c. It can be direct or direct attachment of antibody
i. Direct: we label an antibody which can directly attach to the target cell and then see the antibody by the
attached fluorescent molecule
ii. Indirect: the primary antibody which attaches to the target isn’t labeled, but the secondary antibody (which
is specific for the first antibody) is labeled with the fluorescent molecule
d. Why might we want to use an indirect method instead of a direct? Cost an availability
i. Aometimes our primary antibodies are so precious we don’t want to use more than we have to, and so by
using indirect we can conserve the primary antibodies
XV.
Immuno Fluorescence Analysis [S15]
a. Here is and image of a fibroblast labeled with immunofluorescent antibodies
b. The actin is the target which is glowing
c. The antibodies bind to the actin and give us this fluorescent image
XVI.
Reconstructing an Image [S16]
a. This slide is an example of how it’s not always easy to tell exactly what we’re looking at in microscopy
b. Our image can really vary depending on our perspective, so we need to be creative reconstructing the image
XVII. Untitled [S17]
a. This picture of a glomerulus of the kidney gives a good example of that concept of perspective
b. Depending on how we slice this image, it can significantly change how it appears
XVIII. Histology Virtual Lab [S18]
a. A nice website, with lots and lots of images you can look at for this course
XIX.
Epithelium and Glands [S19]
a. Now, let’s start talking about epithelium
b. Most of what we’ll talk about today is epithelium
c. What is the tissue imaged here? Just basic epidermis (skin)
d. Epidermis is specifically the epithelium in skin
e. Epithelium is a generic term for all the tissues that line our organs – that includes our skin, but also the lining
of our GI tract or respiratory tract
XX.
Functions of Epithelium[S20]
a. So what are the functions of epithelium?
b. Protection: protects us from the outside world
c. Absorption: our GI tract utilizes this function to absorb nutrients and molecules
d. Secretion: many epithelial cells, like glands, secrete various compounds
e. Excetory: kidneys excrete liquids
f. Lubrication: all our internal organs are lubricted, keeping them from getting stuck or causing friction
g. Sensory: many sensory organs are epithelium organs
h. Reproduction: for males, their reproductive cells (sperm) arise from epithelial cells
XXI.
Functions of Epithelium [S21]
a. Duplicate of previous slide - SKIPPED
XXII. Structural Features [S22]
a. These are general features that apply to all epithelium
b. All of our organs are lined with epithelium – our skin is an obvious example, but also the lumen of our GI tract,
our reproductive tracts, our ears, our nasal passages
c. All epithelium sits on a basement membrane – the attachment site of our epithelium
d. Epithelium is avascular – it contains no blood vessels
i. Why would this be important? Because epithelium functions to protect from pathogens, and you want to
keep pathogens away from your circulation, so having epithelium avascular helps avoid infections
e. Cells are normally polarized – that means they two distinct ends of the cell
f. Cells are all attached by specialized cell junctions – critical also for forming a solid and functional barrier
g. They form a boundary between external environment and the remainder of the organ
CLASS: 10:00-11:00
Scribe: Eric Larson and Lauren Morris
DATE:11-1-10
Proof: Eric Larson and Lauren Morris
PROFESSOR: Dr. Cotlin
Introduction to Human Tissues #1
Page 3 of 6
i. That doesn’t always mean between the outside and inside of the body, but sometimes between one organ
and the other
h. All derived from three germ layers
XXIII. Structural Features [S23]
a. Duplicate of previous slide – SKIPPED
XXIV. Domains of a Polarized Cell [S24]
a. This is a nice columnar cell that we might see in the GI tract
b. Here we see the basement membrane, and all the epithelial cells are sitting on that with their apical side
towards the leumen
c. The basolateral region is the side opposite of the apical
XXV. Untitled [S25]
a. This shows tight junctions which are what define cell polarity
b. In most epithelial layers, tight junctions are localized at the apical region
c. The basolateral region is everything else
d. This defines cells in terms of structure (that’s where our barrier is) and function (if molecules are routed to the
apical side of membrane, they’ll stay there and not cross barriers into the basolateral side)
e. So these tight junctions really define functionally what goes on in the cell
f. If something needs to get across the cell from the leumen, it is taken first into apical region and then moved
by transporters to the basolateral side
XXVI. Transport Across Epithelium [S26]
a. Here again we see the tight junctions
b. If something comes in apical side, it must be transported across tight junction and can then be secreted into
basolateral side
c. This is how nearly every cell functions (some exceptions)
XXVII. The Basal Lamina [S27]
a. Here’s a row of epithelium
b. You can see how all of these cells are sitting on a basal membrane
c. A gland is pictured
d. All of those cells are sitting on a basal lamina
e. The basal membrane is the molecular structure, the basal lamina is what we see in a microscope
XXVIII. Functions of the Basal Laminae [S28]
a. The basal lamina is the membrane which always separates epithelium from connective tissue
b. It physically binds the epithelial cells to the connective tissues
c. It is a barrier for diffusing molecules so that epithelial cells can receive nutrients, as well as transport other
substances through the epithelial cells towards the blood
d. It selectively filters molecules
e. It is important in clotting functions, cell growth, and other various functions
XXIX. Epithelium [S29]
a. So this depicts the basement membrane, with epithelial cells sitting on top of it
b. This is the classic way we like to depict it
XXX. Kidney Glomerulus [S30]
a. There are some places in the body where the basement membrane actually connects two cells
i. An example is the kidney glomerulus seen here
b. So we don’t always have connective tissue on the other side of the basment membrane – sometimes two
cells share a basement membrane
XXXI. The Basement Membrane [S31]
a. Here again we have an image of a glomerulus of the kidney
b. Stained with PAS (which stains carbohydrates) – PAS is handy for highlighting the basement membrane
because its often rich in carbohydrates
c. You can see how each epithelial cell is distinctly sitting on a basement membrane
XXXII. Components of the Basal Laminae [S32]
a. So what is the basement membrane? A banding of dense layer and loose layer
b. Two major components of basal laminae: laminin is one, and type IV collagen is the other
c. Collagen type IV and laminin are the major components, with a few accessory components that we don’t
worry about
XXXIII. Major Components of Basal Laminae and Extracellular Matrix (ECM) [33]
a. Points out images of Collagen Type IV, Laminin (cross-shape), accessories (nidogens, fibrillar, fibronectin –
all protein molecules)
b. Glycosaminoglycans and proteoglycans
CLASS: 10:00-11:00
Scribe: Eric Larson and Lauren Morris
DATE:11-1-10
Proof: Eric Larson and Lauren Morris
PROFESSOR: Dr. Cotlin
Introduction to Human Tissues #1
Page 4 of 6
i. GAG: Repeating sugar links, highly branched, shown in red
ii. Proteoglycans: protein molecules with lots of GAGs attached
iii. Aggrecan – protein scaffolding with GAG modifications
iv. Basement membrane is enriched with GAGs – stains well with PAS
XXXIV. Organization of the Basement Membrane [S34]
a. How the major components are put together and interact
b. Red: Collagen Type IV, makes a lattice/sheet
c. Blue: Laminin, makes a second lattice/sheet
d. The other molecules are accessories, keeping everything together
i. Integrins (green): cell-surface proteins, in epithelial cells and bind to basement membrane proteins
e. This image is as if you are viewing underneath the basement membrane
XXXV. Organization, another view [35]
a. Note the sheet of laminin and sheet of collagen type IV
b. Perlecans, entactins, etc. keep everything together
c. Note integrin molecules (cell-surface proteins) that physically attach the epithelium
XXXVI. Epithelial Cell and Basement Membrane [36]
a. Reminder that it’s not as easy as it looks – lots of other molecules are intact too
i. Don’t worry about all the terms
b. Connective tissue is below on this image
i. Lots of collagen bundles and molecules
ii. Collagen type VII – critical for connecting the connective tissue (collagen IV in the matrix) to the basement
membrane; an anchoring protein
1. Looks like it’s sewing it all together
iii. Collagen type IV is the collagen within the connective tissue
XXXVII. Basement Membrane (PAS) [37]
a. Red arrow pointing to basement membrane
b. In the urinary tract
XXXVIII.
EM of Basement Membrane [38]
a. From the Glomerulus
b. Endothelium (labeled En) on one side of BM
i. Epithelium of blood vessels
c. Fused, very thick pronounced BM (labeled as BL)
d. Epithelium is on other side
e. Distinction between basal lamina and basement membrane (she has probably used them interchangeably)
i. Basal Lamina
1. Molecular makeup that we can’t physically see
2. Cells secrete a basal lamina, they secrete the sheets of matrix
3. If you looked under light microscopy with no staining, you would not see it very distinctly
4. The molecular name is collectively the basal lamina
ii. Basement Membrane
1. Referred to when we look at images and can actually detect it
2. The global structure where we look at all of it, the proteins with the sugars all together
3. Not as thick as it appears – it’s really just two sheets of proteins
4. This term is used a lot more because this is what we can actually detect
XXXIX. Classification of Epithelial Tissue [39]
a. Can define epithelial tissue based on the number of cell layers, the shape of the cells, whether or not they
have specialized structures (cilia, microvilli)
b. Cell layers can be classified
i. Simple layer = one layer structure; all cells sit at the BM
ii. Stratified = two or more layers
1. Basal layer of cells are sitting on the BM, but not all cells
iii. Pseudostratified = looks like it’s stratified but it’s really a simple layer
1. All cells sit at the BM
2. Not all of them reach the lumen necessarily
XL.
Classification of Epithelium [40]
a. Can classify based on number of layers: Simple or Stratified
b. Can classify based on shape:
i. Squamous: flat sheet of cells, look like a fried egg where the yolk is the nucleus
1. Non-keratinized
CLASS: 10:00-11:00
Scribe: Eric Larson and Lauren Morris
DATE:11-1-10
Proof: Eric Larson and Lauren Morris
PROFESSOR: Dr. Cotlin
Introduction to Human Tissues #1
Page 5 of 6
2. Keratinized
ii. Cuboidal: cube shaped
iii. Columnar: taller than they are wide with nucleus towards the basal lateral region
c. Note pseudostratified: assortment of heights of cells, nuclei look like they’re stratified but all cells sit at BM
d. Note stratified squamous, stratified cuboidal, stratified columnar, transitional stratified
e. Always define the epithelial layer by the outermost layer (luminal-most layer)
i. Stratified columnar: called columnar even though the most basal cells look cuboidal
f. Transitional stratified: can look in between stratified squamous and stratified cuboidal
i. Located in bladder, lining ureters, bladder, urethra
ii. Can readily hold fluids
iii. When it’s relaxed, not holding a lot of tension, the cells look cuboidal (puffy)
iv. As the lumen collects more material (urine), those cells flatten out dramatically to make room and look
squamous
XLI.
Simple Squamous Epithelium [41]
a. Epithelium sitting on a BM
b. Lamina propria: generic term for the loose connective tissue that underlines epithelium
c. Found in kidney, lines blood and lymphatic vessels and bone marrow
i. Endothelium = specific to blood vessels, simple squamous
d. When looking at the simple squamous cell, all we really see is the nuclei (A)
i. Not much cytoplasm, don’t see a bulk of a cell
XLII.
Simple Epithelium [42]
a. Can read this slide later if you want
b. Shows tube system with simple layers
XLIII. Simple Squamous Epithelium [43]
a. This is as if we unrolled a sheet of simple squamous (unrolled a blood vessel)
b. Fried egg appearance, central nucleus
XLIV. Simple Squamous epithelium of a blood vessel [44]
a. Stained with PAS and H
i. Can ID nuclei and carbohydrates
ii. Very thin cytoplasmic material
XLV. Simple Squamous epithelium [45]
a. Smooth muscle is below the epithelial cells
XLVI. Simple Squamous epithelium [46]
a. Thin layer with nucleus to the side
b. This is the previous slide zoomed in
XLVII. Simple Squamous Epitthelium [47]
a. Blood vessel is the white part in the middle (with a crease)
b. Simple layer of epithelium outlines the vessel
i. A lot of material goes in and out of blood
ii. Want as simple and thin layer as possible for that material to cross
XLVIII. Simple cuboidal epithelium [48]
a. Cube looking tissue
b. A = collecting duct
c. B = salivary duct, looks kind of stratified
d. C = packing of cells
XLIX. Simple Cuboidal Epithelium [49]
a. Collecting duct
b. Don’t see all of the nuclei due to the spacing of nuclei, and can’t see outline of all the cells due to staining
pattern
i. But you can tell it’s cuboidal because they are as tall as they are wide
ii. You’ll never have a columnar on its side so it’s short and squat
iii. They will be cuboidal or taller than they are wide
L.
Simple Columnar Epithelium [50]
a. A = kidney
b. C = intestine, chain of nuclei
c. B = compact, not as much nice delineation but it is not a stratified layer
LI.
Simple Columnar Epithelium [51]
a. Epithelium with cilia; this is the lining of intestinal tract
b. Note the chain of nuclei
CLASS: 10:00-11:00
Scribe: Eric Larson and Lauren Morris
DATE:11-1-10
Proof: Eric Larson and Lauren Morris
PROFESSOR: Dr. Cotlin
Introduction to Human Tissues #1
Page 6 of 6
c. Yellow arrow = goblet cell
d. Red arrow = BM
e. Goblet cells and BM would stain pink in PAS
f. Random cells above BM but below the chain of nuclei = population of stem cells in basal region b/c epithelial
cells are always turning over
LII.
Simple Columnar Epithelium [52]
a. A bunch of goblet cells
b. Nuclei are compact, in a chain
LIII.
Simple Columnar Epithelium [53]
a. Stained with PAS, similar picture
i. BM = blue line underneath epithelium cells
ii. Lumen in center = white
iii. Blue arrow = goblet cells
iv. Yellow arrow = glycocalyx border
1. Protein with carbohydrate attachments have attachments on extracellular side
2. They are put on initially in the ER lumen, processed in golgi, and then end up on the cell surface
LIV.
Pseudostratified Epithlium [54]
a. In respiratory passages (nasal cavity through bronchi and male reproductive tract)
b. All sit at BM, but not all extend all the way to the lumen
i. Looks like you have multiple laters of cells, nuclei
LV.
Pseudostratified Ciliated Columnar Epithelium [55]
a. Cilia can be see at the top
b. This is a simple layer, one layer of cells at all different heights
[End 52:50 mins]