Cells and tissues by duggybrown

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									CELLS AND TISSUES
       1
ECTODERM, MESODERM AND ENDODERM

During gastrolation, three major cell lineages are
established:

Ectoderm, endoderm and mesoderm.

Following gastrolation various cell lineages are derived
from these primary cell types.
EMBRYONIC SOURCES

  ECTODERM – brain, skin

  ENDODERM – kidney, muscle

  MESODERM – liver, gut
                    Ectoderm, endoderm and mesoderm
                                  zygote
                                 blastula
                                 gastrula
                ECTODERM                                           ENDODERM
epidermis and                 brain and                               embryonic gut
associated structures         nervous               inner lining of            inner lining of
(skin, hair, nails etc.)      system                digestive tract             respiratory
                                                                                    tract
                                                                       glands
                                                                     including
                                                                liver & pancreas
                                      MESODERM
          notochord                                           somatic cells
                                                          muscle     outer covering
                                                                     of internal organs
                    dermis              mesenchyme
              (inner skin layer)      (migratory cells)        bones & cartilage
                                                          excretory system         gonads
                                      circulatory system
                                      heart, blood vessels
EPITHELIA
    epithelia are represented in organs of
    all three embryological layers


MESENCHYME connective tissues

MUSCLE skeletal, smooth, cardiac

NEURAL TISSUES nerves and their support

BLOOD stem cells and their progeny
Basic organisation of epithelial tissues




         * *         *

                             nuclei
                             Nuclei

                            basement membrane
           Organisation of epithelial tissues
SIMPLE                                COMPOUND
Squamous                              Transitional
(some ducts)                          (bladder)
Cuboidal
(glands)
Columnar                               Stratified
(gut)                                 squamous
                                      (uterine cervix)


Pseudostratified                       Keratinised
(trachea)                              squamous
                                       (skin)
DIFFERENTIATION OF CELLS OF THE SKIN




                                 PROLIF.




                                 BM
            Organelles found in most cells
                             1.    Nucleus, euchromatin
                             2.    Nucleus, heterochromatin
                             3.    Nuclear membrane
                             4.    Plasmamembrane
                             5.    Lamellipodium
                             6.    Pinocytotic vesicle
nucleolus                    7.    Phagocytic vesicle
                             8.    Vacuole
                             9.    Rough endoplasmic reticulum
                             10.   Golgi apparatus
                             11.   Mitochondria
                             12.   Transport vesicles
                             13.   Secondary lysosomes
                             14.   Teleolysosome
                             15.   Extracellular matrix - collagen


                              THIS IS A TISSUE MACROPHAGE
Basement membrane (extracellular)
Connective tissue components (extracellular)


                 ORGANELLES
Plasma membrane, lamellipodia
Nucleus – euchromatin/heterochromatin. Pores
Nucleolus
Mitochondria
SER
Ribosomes, RER and Golgi apparatus
Vacuoles and lysosomes
           The plasmamembrane
               a lipid bilayer




Freeze-fracture technique
              Electron micrograph of a mast cell




Cytoplasmic
   granules

                                             Heterochromatin

Euchromatin
                                              Nuclear
                                               membrane
MITOCHONDRION
           FUNCTIONS OF THE
            MITOCHONDRION

    – Location of Krebs cycle enzymes
•   Traps chemical energy derived from food
•   Glucose to CO2 and water, plus energy (E)
•   Through electron-transfer cytochtomes
•   Fixes E in adenosine triphosphate (ATP)
•   ATP is then utilizable by the cell
        MITOCHONDRIAL DNA


• Circular chromosomes, small amounts of DNA
• Encoding respiratory chain and oxidative
  phosphorylating proteins + some RNAs
• Genome contains 2RNA genes, 22 tRNA genes and
  13 protein coding sequences
• Mitochondrial genetic code is somewhat unique
• Inheritance is ONLY through the maternal line
• High rate of mutation – thus, population variations
Export of a synthesised product
      SER
SER
           SER

Smooth endoplasmic reticulum

 common in cells that produce
 steroid hormones

 liver
Pancreatic acinar cells: RER and granules




            RER         granules
ribosomes




            RER
Birbeck granules – diagnostic of histiocytes
Weibel-Palade bodies


are small organelles specific to endothelial
cells. Helpful in the diagnosis of poorly
differentiated angiosarcomas
Formation of vacuoles and
   binding membranes
     lumen

1.
     lumen

2.
     lumen
3.
Lysosomes and peroxisomes degrade matter inside the cells
with INTRACELLULAR enzymes




                                  Heterolyosomal degradation




        Heterolyosomal degradation
Tumour cell with two phagocytosed apoptotic bodies
Primary lysosome – contains lytic enzymes
Phagocyte




    secondary lysosome
                           teleolysosome



In the teleolysosome the enzymes have degraded the contents
           30.9.05
With 3MED564A I only got this far!
THE CYTOSKELETON


  Actin microfilaments

  Intermediate filaments

  Microtubules
                          Microvillus border



Intercellular
Junctions
                                Microfilaments
            *
                                Intermediate
                                filaments




Cell/BM
junctions       *   Basement membrane
In the adherent junction microfilaments are tethered
to the cell membrane through a tripartite complex:



Classical cadherin, coupled directly through its
cytoplasmic tail to

beta-catenin thence to

alpha-catenin thence to

actin
DESMOSOMES anchor intermediate filaments


3D scaffolding for mechanical strength


Respond to environmental and cellular
 information by modulating their assembly state


Possibly have signalling functions
Desmosomes between adjacent epithelial cells
    MAIN BUILDING BLOCKS OF DESMOSOMES
   COME FROM THREE MAJOR GENE FAMILIES

Desmosomal cadherins              -       desmogleins
                                          desmocollins

Armadillo family                  -       plakoglobin
(nuclear & junctional proteins)           plakophilins 1-3


Plakins                           -       plectin
                                          desmoplakin

       plus enveloplakin and periplakin
A microfilament, an intermediate filament and a microtubule


                                            ~ 5nm


                                            ~ 10nm



                                            ~ 25nm

                                            (diameters)
             Microvilli

             Zonular occludens

             Zonular adherens

desmosomes


             Gap junction



             Infoldings of the
             plasma membrane


             Basement membrane
Junctional complex of epithelial cells

     tight
     junction

     adherent
     junction

     desmosome



     gap junction
microvilli




             Actin microfilament
             a
             c core rootlets
             t
             i
             n
microvilli




             VILLUS
Cells of the fallopian tube have both cilia and microvilli




                                            cilia

                                            microvilli
                  central core
                                 plasma-membrane
   shared
 heterodimers


microtubule                          dynein
 doublet                             tails

     nexin




 central sheath                   radial spokes




  CILIUM CONSTRUCTION
Pseudostratified epithelium of the trachae




                               Cilia
                               Pseudostratified
                               cells
     THE CENTROSOME




LS of centriole   TS of centriole
The centrosome is made up of two centrioles


                                                    centrioles




Microtubular structure of the centrioles is 9 interlinked triplets
4           1




            2



            3

    6   5
TISSUES
SMALL INTESTINE
Haematoxylin and eosin (h&e) of small intestine

                                   villi




                                   absorptive cells


                                   goblet cell


                                   crypt
                              goblet
                              cell


                             absorptive
                             cell



SMALL INTESTINE - duodenum
Haematoxylin and eosin (h&e) of large intestine

                                   Note
                                   NO villi
                                   Much higher
                                   proportion of
                                   goblet cells


                                   Some
                                   inflammatory
                                   cells in the
                                   lamina propria
                                   here
H & E section of normal appendix

                        mucosa

                        crypts of Lieberkuhn

                        lamina propria

                        muscularis mucosa

                        submucosa

                        lymphatic nodules, with
                        germinal centres

                        muscularis externa

                        serosa
Endocrine cell in the gastrointestinal tract
LUNG
Haematoxylin & eosin section of normal lung


                                       pulmonary
                                          vein

                                        bronchiole
                                        pulmonary
                                        artery
ELECTRON MICROGRAPH OF NORMAL LUNG

Alveolar
                        ALVEOLUS
macrophage
                                   Type I
             ALVEOLUS              pneumocyte


                                      Capillaries



Type II
pneumocyte
                        ALVEOLUS
             ALVEOLUS
      H&E section of lung in tuberculosis




(we do this in more detail in ‘Chronic Inflammation’)
LIVER
             Liver terminology

Afferent blood supply - hepatic portal vein (HPV)
                        hepatic artery

Efferent blood        - central vein


Bile ducts
Portal tract
Space of Disse
Canals of Hering
HISTOLOGY OF BLOOD VESSELS


Arteries – carry blood away from the heart

Postarterial capillaries


Capillaries – bathe tissues and cells in nutrients
Venous capillaries

Veins - carry blood to the heart
CELLS OF THE LIVER

Parenchyma -   hepatocytes


Stroma     -   endothelial cells
               Kupffer cells
               stellate cells
Kupffer cell


Stellate cell
Space of Disse

Bile canaliculus
CELLS OF THE LIVER

                KC Kupffer cell
                EC endothelial cell
                RBC red blood cell
                PSC stellate cell
                SD space of Disse
                BC bile canaliculus
Diagram of liver cell arrangement
PLAN OF LIVER HISTOLOGY



              PV
                                           cv



       hepatocytes



 BD = bile duct, PV = portal vein, CV = central vein
 H & E section of normal liver

hepatocytes




                CV



       PV



  PV = portal vein, CV = central vein
     Electron micrograph of a hepatocyte




Hepatocytes have a wealth of organelles. Check them
 out with the list at the beginning of the lecture
hepatocyte




space of
Disse

endothelial
cytoplasm

lumen of sinusoid
IN THE LIVER:
Most simple capillaries have endothelium, BM, cover


Larger vessels have added complexity.
           pericytes
           smooth muscle layers (arteries)
           valves (veins)
           elastin
Capillaries consist of endothelial cells,
  resting on a basement membrane

                                  bm
                                       B
                                       M
               LUMEN

                        e
                                       lumen of
                                       sinusoid




                                       fenestrae


endothelial cell




    Liver sinusoidal endothelium – sieve plate
Kupffer cell with phagocytosed apoptotic body
    hepatocyte




hepatocyte



    Hepatic stellate cell
                            collagen fibres




                              cell nucleus




                              cytoplasm




Active fibroblast, producing collagen

								
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