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Vertebrate Histology Exam 1

front 1

Histology

back 1

Purpose of course in histology is to understand the microanatomy of cells, tissues, and organs and to correlate structure with function.

front 2

Histological Sections

back 2

  • Thin, flat slices of fixed and stained tissues or organs mounted on glass slides
  • Tissues and organs composed of cellular, fibrous, and tubular structures
  • Cells: variety of shapes and sizes, may be layered
  • Fibrous: solid structures found in connective, nervous, and muscle tissues; “fibers”
  • Tubular: hollow, represent blood vessels, ducts, or glands

front 3

Histological Sections

back 3

Transverse/cross section

  • Perpendicular to the longitudinal axis

Longitudinal/ sagittal section

  • Parallel to the longitudinal axis
  • We have to interpret a 2-dimensional image into a 3-dimensional structure. The way a section passes through a tissue can drastically alter its appearance.

front 4

Planes of section of a round object:

back 4

why a nucleus may not always be visible & object size misjudged

front 5

Planes of section of a tube:

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# of tubes, # cell layers of wall can be misjudged

front 6

Convoluted tubules of testis in different planes of section:

back 6

some are round and some are oblique

front 7

Tissue preparation

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  • Fixation to preserve structure: chemical or mixture of chemicals that permanently preserves the tissue structure (e.g. formaldehyde, alcohols, organic solvents)
  • Terminates cell metabolism
  • Prevents enzymatic degradation of tissue and cells by autolysis
  • Kill pathogenic microorganisms
  • Hardens tissue via cross-linking or denaturing proteins

front 8

Tissue preparation

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  • Dehydration & Clearing: increasing concentrations of ethanol typically followed by xylene
  • Makes tissue transparent
  • Allows embedding medium to penetrate the tissue more easily

front 9

Tissue preparation

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  • Embedding specimen in paraffin (wax) or plastic polymer for sectioning (or tissue may be frozen for immediate medical diagnosis)
  • Allows for thin sections to be made while keeping tissue structures intact

front 10

Tissue preparation

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  • Sectioning of embedded specimen & mounting onto glass slides
  • 5-15 μm thickness (paraffin)
  • 0.1 µm or less (plastic polymer

front 11

Tissue preparation

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  • Staining
  • Paraffin must be dissolved if used—dyes are hydrophilic
  • Visualize cell structures by using dyes that bind to specific properties of biomolecules found in cells, tissues, and organs
  • Basic (cationic) stains stain basophilic structures, e.g. nucleic acids
  • Acidic (anionic) stains stain acidophilic structures, e.g. cytoplasmic proteins
  • Most common: hematoxylin and eosin (H & E)—what we’ll see most often in our book and in lab

front 12

H & E stain: most commonly used stain in histology

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  • Hematoxylin (basic stain)
  • Nuclei stain blue to purple
  • Eosin (acidic stain)
  • Cytoplasm stains pink or red
  • Collagen fibers stain pink
  • Muscles stain pink

front 13

Masson’s Trichrome stain: highlights connective tissue

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  • Nuclei stain black or blue black
  • Muscles stain red
  • Collagen and mucus stain green or blue
  • Cytoplasm of most cells stains pink

front 14

Periodic Acid-Schiff Reaction (PAS): highlights secretions, basement membranes, and microvilli

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  • Glycogen stains deep red or magenta
  • Goblet cells in intestines and respiratory epithelia stains magenta red
  • Basement membranes and brush borders (microvilli) in kidney tubules stain pink

front 15

Elastic Tissue stain: highlights elastic fibers

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  • Elastic fibers stain jet black or brown
  • Nuclei stain gray
  • Remaining structures stain pink

front 16

Mallory-Azan stain: highlights connective tissue

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  • Fibrous connective tissue, mucus, and hyaline cartilage stain deep blue
  • Erythrocytes stain red-orange
  • Cytoplasm of liver and kidneys stains pink
  • Nuclei stain red

front 17

Wright/Giesma stain: highlights blood cells

back 17

  • Erythrocyte cytoplasm stains pink
  • Lymphocyte nuclei stain dark purple-blue with pale blue cytoplasm
  • Monocyte cytoplasm stains pale blue and nucleus stains medium blue
  • Neutrophil nuclei stain dark blue

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Wright/Giesma stain: highlights blood cells

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  • Eosinophil nuclei stain dark blue and granules stain bright pink
  • Basophil nuclei stain dark blue or purple, cytoplasm stains pale blue, and granules stain deep purple
  • Platelets stain light blue

front 19

Cajal’s (or Bielschowsky’s) and Del Rio Hortega’s Methods (silver and gold stains): highlights nervous tissue

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  • Myelinated and unmyelinated fibers and neurofibrils stain blue-black, brown, or gold
  • General background nearly colorless
  • Astrocytes stain black

front 20

Osmic Acid (osmium tetroxide) stain: highlights lipids

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  • Lipids generally stain black
  • Including lipids in myelin sheath of nerves

front 21

Iron Hematoxylin & Alcian Blue Stain: highlights connective tissue, mucus, & muscle and cell membrane structures

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  • Cell membranes, muscle striations, & intercalated discs stain black
  • Connective tissue fibers & mucus stain dark blue
  • Smooth muscles stain light pink
  • Nuclei stain dark pink
  • Cytoplasm stains light pink

front 22

Iron Hematoxylin & Alcian Blue Stain: highlights connective tissue, mucus, & muscle and cell membrane structures

back 22

  • Cell membranes, muscle striations, & intercalated discs stain black
  • Connective tissue fibers & mucus stain dark blue
  • Smooth muscles stain light pink
  • Nuclei stain dark pink
  • Cytoplasm stains light pink

front 23

Microscopy

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  • Magnifies an image and allows visualization of greater detail
  • Simple = 1 lens
  • Compound = multiple lenses
  • Resolving power (resolution): ability of lens or optical system to produce separate images of closely positioned objects
  • Can you tell the difference between 2 adjacent objects (2-point discrimination)?—depends on power of microscope and distance between objects

front 24

Microscopy

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  • Resolution dependent on:
  • Optical system
  • Wavelength of light source
  • Specimen thickness
  • Quality of fixation
  • Staining intensity

front 25

Microscopy

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Eye Versus Instrument Resolution

Distance between resolvable points

Human eye: 0.2 mm

Bright-field microscope: 0.2 µm

SEM: 2.5 nm

TEM Theoretical Tissue Section: 0.05 nm

1.0 nm

Atomic force microscopy: 50 pm

front 26

Microscopy:

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series of lenses that focus and magnify a beam of light or electrons

front 27

Microscopy

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  • Bright-field microscope: what we use in laboratory (see more in-depth description in Lab #1 Exercise Handout)
  • Light source: illuminates specimen
  • Condenser lens: focuses light onto specimen
  • Stage: where specimen is placed
  • Objective lens: gathers light passing through specimen
  • Ocular lens: where image is examined

Visualize

  • Nucleus
  • Cytoplasm
  • Cell membrane
  • Organelles are stain dependent—not typically seen with H & E

front 28

Microscopy

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  • Transmission Electron Microscopy (TEM): beam of electrons to produce an image
  • Uses thinner sections: ~100nm
  • Light areas are where electrons pass through specimen
  • Dark areas are where electrons are absorbed or scattered
  • Scanning electron microscopy: electron beam passes across specimen surface (topography of cells or tissues)

front 29

The Cell

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  • Living organisms contain multiple cell types to maintain homeostasis
  • Common structural features in all cells (organelles)—see also Graphic 1-2
  • Quantity, distribution, and appearance of organelles will differ with type of cell and cell’s function

front 30

Mammalian cells

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  • Cytoplasm: dense, fluid-like medium
  • Cell (plasma) membrane: barrier between internal and external environments
  • Organelles and intracellular elements: suspended in cytoplasm, each has a unique special function
  • Nucleus: control center
  • Mature red blood cells DO NOT have one
  • Microtubules: cytoskeleton
  • Microfilaments: cytoskeleton
  • Membrane-bound secretory granules and organelles
  • Ingested material

front 31

Organelles: Membrane-bound

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Membrane-bound

  • Nucleus (typically only organelle visible with light microscopy)
  • Mitochondria
  • Endoplasmic reticulum (ER): Smooth & Rough
  • Golgi apparatus
  • Endosomes
  • Lysosomes

front 32

  • Nucleus

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  • the centrally located compartment of eukaryotic cells that is bounded by a double membrane and contains the chromosomes
  • enclosed by the nuclear envelope, composed of an inner and an outer nuclear membrane with an intervening perinuclear cistern. The outer nuclear membrane is studded with ribosomes and is continuous, in places, with the RER.
  • the central and most important part of an object, movement, or group, forming the basis for its activity and growth.

front 33

  • Mitochondria

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  • energy-generating organelles that contain the enzymes of the citric acid cycle, the respiratory chain, and oxidative phosphorylation
  • composed of an outer and an inner membrane with an intervening compartment between them known as the intermembrane space. The inner membrane is folded to form flat (or tubular in steroid-manufacturing cells) shelf-like structures known as cristae and enloses a viscous fluid-filled space known as the matrix space
  • function in the generation of ATP, utilizing a chemiosmotic coupling mechanism that employs a specific sequence of enzyme complexes and proton translocator systems (electron transport chain and the ATP synthase-containing elementary particles) embeded in their cristae
  • generate heat in brown fat instead of producing ATP
  • Also assist in the synthesis of certain lipids and proteins; they possess the enzymes of the TCA cycle, circular DNA molecules, and matrix granules in their matrix space
  • increase in number by undergoing binary fission

front 34

  • Endoplasmic reticulum (ER): Smooth & Rough

back 34

  • SER: functions in the synthesis of cholesterols and lipids well as in the detoxification of certain drugs and toxins (such as barbiturates and alcohol). Additionally, in skeletal muscle cells, this organelle is specialized to sequester and release calcium ions and thus regulate muscle contraction and relaxation
  • RER: whose cytoplasmic surface possesses receptor molecules for ribosomes and signal recognition particles (known as ribophorins and docking proteins, respectively), is continuous with the outer nuclear membrane. The RER functions in the synthesis and modification of proteins that are packaged, as well as in the synthesis of membrane lipids and proteins.

front 35

  • Golgi apparatus

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  • a system of concentrically folded membranes found in the cytoplasm of eukaryotic cells; functions in secretion from the cell by exocytosis
  • the Golgi apparatus is composed of a specifically oriented cluster of vesicles, tubules, and flattened membrane-bounded cisternae

front 36

  • Endosomes

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  • are intermediate compartments within the cell, utilized in the destruction of endocytosed, phagocytosed, or autophagocytosed materials as well as in the formation of lysosomes
  • possess proton pumps in their membranes, which pump H+ into the endosome, thus acidifying the interior of this compartment
  • are intermediate stages in the formation of lysosomes

front 37

  • Lysosomes

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  • a membrane enclosed organelle originating from the golgi apparatus and containing hydrolytic enzymes
  • a formed by the utilization of late endosomes as an intermediary compartment
  • both lysosomal membranes and lysosomal enzymes are packaged in the TGN
  • they are delivered in seperate clathrin-coated vesicles to late endosomes, forming endolysosomes, which then mature to become lysosomes

front 38

  • Peroxisomes

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  • peroxisomes are membrane-bounded organelles housing oxidative enzymes such as urate oxidase, D-amino acid oxidase, and catalase
  • these organelles function in the formation of free radicals (superoxides), which destroy various substances
  • they protect the cell by degrading hydrogen peroxide by catalase
  • they also function in detoxification of certain toxins and in elongation of some fatty acids during lipid synthesis

front 39

Organelles: Not membrane-bound

back 39

Not membrane-bound

  • Ribosomes
  • Basal bodies
  • Centrioles
  • Centrosomes
  • Cytoplasmic inclusions

front 40

  • Ribosomes

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  • small, bipartite nonmembranous organelles that exist as individual particles that do not coalesce with each other until protein synthesis begins
  • the 2 subunits are of unequal size and constitution. The large subunit is 60s, and the small subunit is 40s in size
  • each subunit is composed of proteins and r-RNA, and together, they function as an interactive "workbench" that not only provides a surface upon which protein synthesis occurs but also acts as a catalyst that facilitates the synthesis of proteins

front 41

  • Basal bodies

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  • each cilium arises from a structure known as the basal body that resembles a centriole in that it is composed of 9 microtubule triplets
  • an organelle that forms the base of a flagellum or cilium

front 42

  • Centrioles

back 42

  • A centriole is a small set of microtubules arranged in a specific way. There are nine groups of microtubules. When two centrioles are found next to each other, they are usually at right angles. The centrioles are found in pairs and move towards the poles (opposite ends) of the nucleus when it is time for cell division
  • a paired organelle that helps organize the microtubules in animal and protist ells during nuclear division

front 43

  • Centrosomes

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  • are associated with the nuclear membrane during the prophase stage of the cell cycle. In mitosis the nuclear membrane breaks down and the centrosome nucleated microtubules can interact with the chromosomes to build the mitotic spindle
  • the major microtubule organizing center of an animal cell

front 44

  • Cytoplasmic inclusions

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  • lipids, glycogen, secretory granules, and pigments, are also consistent constitutes of the cytoplasm

front 45

Cytoskeleton

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  • Network of protein filaments and tubules that extend throughout cytoplasm
  • Structural framework of cell

3 filament types

  • Microfilaments/actin (forms core of microvilli)
  • Intermediate filaments
  • Microtubules (forms mitotic spindles, cilia, and flagella)

front 46

Ciliated vs. nonciliated epithelium

back 46

front 47

Cell Components & Sizes

back 47

front 48

Cell Components

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front 49

Cell Components

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front 50

Special features of certain cells

back 50

Apical vs. basal modifications of epithelial cells

  • Cilia
  • Microvilli
  • Basal infoldings

front 51

Apical: Cilia and microvilli

back 51

front 52

Basal: Basal Infoldings

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front 53

Basal: Basal Infoldings of ion-transporting cells

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front 54

Basal: Basal Infoldings ion-transporting cells

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front 55

Special features of certain cells

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  • Junctional complexes: hold cells together into tissues (barrier and cell-to-cell communication)—used by epithelial and connective tissues
  • Lateral and basal surfaces of cells
  • Zonula occludens (tight junctions)
  • Zonula adherens
  • Desmosomes
  • Hemidesmosomes
  • Gap junctions

front 56

Lateral: Junctional Complexes

back 56

front 57

Describing Normal Cells

back 57

  • Cell Shapes
  • Features of the cytoplasm
  • Features of the nucleus

front 58

Cell Shape

back 58

front 59

Basophilic vs. Acidophilc Cytoplasm

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  • Basophilia is often seen in cells with increased rER for protein synthesis.
  • Acidophilia is often seen in cells with increased mitochondria

front 60

Granules & Lipid Droplets in Cytoplasm

back 60

  • Secretory granules with H & E
  • Normal cytoplasm with H & E
  • Lipid droplets with H & E

front 61

  • Secretory granules with H & E

back 61

front 62

  • Normal cytoplasm with H & E

back 62

front 63

  • Lipid droplets with H & E

back 63

front 64

Euchromatic vs. Heterochromatic Nuclei

back 64

Euchromatic nuclei

  • Lightly staining chromosomes in the nucleus
  • Genes are accessible for transcription

Heterochromatic nuclei

  • Darkly staining chromosomes in the nucleus
  • Genes are NOT being transcribed

front 65

Nucleoli

back 65

  • Nucleoli indicate active protein synthesis so they appear prominently in euchromatic nuclei

front 66

Simple vs. Segmented Nuclei

back 66

Simple nuclei are a single structure, usually round/oval or indented.

front 67

Simple vs. Segmented Nuclei

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Segmented nuclei are often seen in white blood cells and are 2+ lobes connected together.

front 68

Describing Abnormal Cells & Tissues

back 68

  • Presence of inflammation
  • Markers of cell death—apoptotic or necrotic
  • Changes in cell size, shape, or number
  • Presence of abnormal lipids, water, or pigments

front 69

Acute vs. Chronic Inflammation

back 69

  • Both involve an influx of immune cells into a tissue that normally are not there
  • Acute: active, infection with abundance of neutrophils (abscess is a collection of neutrophils)
  • Chronic: infectious process lasting weeks to months involving lymphocytes, plasma cells, mast cells, & eosinophils

front 70

Ulcer

back 70

  • Ulcers are a break in the epithelial tissue lining of an organ creating a crater-shaped lesion
  • Causes:
  • Infection
  • Chemical exposure
  • Prolonged pressure
  • Compromised blood vessels

front 71

Apoptosis vs. Necrosis

back 71

  • Apoptosis is programmed cell death initiated within nucleus & mitochondria of cell—nuclear fragmentation without inflammation.
  • Necrosis is an irreversible cell death caused by cell injury—cells rupture & leak into extracellular space causing inflammation.

front 72

Types of Necrosis

back 72

  • Caseous necrosis
  • Coagulative necrosis
  • Fat necrosis
  • Liquefactive necrosis

front 73

  • Caseous necrosis

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  • Obliteration of tissue structure (holes) & presence of neutrophils caused by infections

front 74

  • Coagulative necrosis

back 74

  • Cells appear to be intact, but nuclei are absent seen in heart attacks & kidney injury.

front 75

  • Fat necrosis

back 75

  • Seen only in adipose tissue, where adipocyte death from trauma or enzymatic digestion releases lipids into extracellular space and accumulates in macrophages.

front 76

  • Liquefactive necrosis

back 76

  • Bacterial infections or injury in the central nervous system.

front 77

Pyknosis

back 77

  • Seen with apoptosis and necrosis
  • Morphological change occurring in the nucleus of an irreversibly damaged cell.
  • Condensation of chromatin & increased basophilia within the nucleus

front 78

Hyperplasia vs. Hypertrophy

back 78

  • Hyperplasia is an increase in cell number.
  • Hypertrophy is an increase in cell size.

front 79

Atrophy

back 79

  • Atrophy is a decrease in cell size (opposite of hypertrophy).
  • Causes: denervation; decreased use, blood supply, or nutrients; pressure

front 80

Steatosis (fatty change) vs. Hydropic change

back 80

  • Steatosis is an abnormal collection of lipid often seen in liver cells.
  • Hydropic change is a reversible cell injury hallmarked by cell swelling due to ion-pump function.

front 81

Amyloid accumulation

back 81

Amyloid is an abnormal protein that accumulates in many diseases

  • Alzheimer’s disease
  • Lymphocyte cancers
  • Chronic inflammation

Accumulation often disrupts function of the cells leading to their death

front 82

Anthracosis vs. Melanin accumulation

back 82

  • Antrhacosis is an exogenous carbon pigment found in macrophages following exposure to smoking or air pollution.
  • Melanin is a pigment produced by skin cells and may accumulate in macrophages during chronic skin inflammation.

front 83

Epithelium & Glands

back 83

front 84

4 basic tissue types

back 84

  • Connective tissue
  • Muscle tissue
  • Nervous tissue
  • Epithelial tissue (focus of this chapter)

front 85

Epithelial tissue (epithelium; epithelia)

back 85

  • Consists of sheets of cells resting on basement membrane
  • Cells contact each other via cell junctions
  • Covers external body surfaces
  • Lines internal body cavities and ducts

front 86

Epithelial tissue (epithelium; epithelia)

back 86

  • Forms glands, organs, and specialized receptor cells (smell, taste, hearing, vision)
  • Nonvascular
  • O2, nutrients, and metabolites diffuse from blood vessels in underlying loose connective tissue
  • Classification based on morphological characteristics (cell shape and layers)
  • Structure varies with function of tissue

front 87

Epithelial tissue (epithelium; epithelia)

back 87

  • Cells are close together and present at a free surface:
  • Exterior of body
  • Outer surface of many internal organs
  • Lining of body cavities, tubes, and ducts
  • Open to exterior: Mouth, nose, respiratory tract
  • Enclosed in body: Pleural, pericardial, and peritoneal cavities & tubes of cardiovascular system

front 88

Classification of Epithelia

back 88

front 89

Epithelial tissue in different organs

back 89

front 90

Epithelial tissue (epithelium; epithelia)

back 90

  • Single or multiple layers
  • Cells joined by specialized cell junctions -->barrier (main function) between free surface and adjacent loose connective tissue
  • Minimal intercellular space
  • Other functions: regulate material exchange and produce and secrete chemicals

front 91

Epithelial tissue can be classified based on structure or function.

back 91

We will identify epithelial tissue based on structure for this course.

front 92

Basic organization of epithelial tissue

back 92

front 93

Epithelial cells have polarity

back 93

  • Apical domain (free surface): motility, absorption, and secretion
  • Lateral domain (sides of cell): communication & anchor to adjacent cells
  • Basal domain (attaches to basement membrane): anchor to underlying loose connective tissue
  • Each domain has different membrane composition (lipid and proteins)

front 94

Apical surface modifications

back 94

Motility

  • Cilia (uterine tubes, uterus, and tubes of respiratory system)

Absorption

  • Microvilli (small intestine and kidney)
  • Stereocilia: long, nonmotile, branched microvilli (epididymis, vas deferens, and hair cells of inner ear)

front 95

Classification of epithelium

back 95

Based on shape of cells and number of cell layers

Shape of surface cells

  • Squamous (flattened; width > height)
  • Cuboidal (round; width = height)
  • Columnar (height > width)

Cell layers

  • Simple (single layer)
  • Stratified (multiple layers)
  • Pseudostratified (single layer of cells but not all cells reach free surface)—appear as multiple layers

front 96

Classification of epithelium: simple

back 96

front 97

Classification of epithelium: stratified

back 97

front 98

Simple squamous epithelium

back 98

  • One layer of flattened cells
  • Mesothelium: covers external surfaces of digestive organs
  • Endothelium: covers lumina of heart chambers, blood vessels, and lymphatic vessels

front 99

Simple squamous epithelium: mesothelium surface view

back 99

Flat cells tightly adhered to one another.

front 100

Simple squamous epithelium: transverse section

back 100

Flat cells with purple nuclei and pink cytoplasm.

front 101

Simple cuboidal epithelium

back 101

Lines small excretory ducts in different organs

  • Provides sturdiness and protection

Line proximal tubules of kidneys (apical surface has a brush border of microvilli)

  • Transport and absorption of filtered substances

front 102

Simple squamous and simple cuboidal epithelia

back 102

front 103

Simple columnar epithelium

back 103

Covers digestive organs (stomach, small and large intestines, and gall bladder)

  • Produce and secrete mucus

Microvilli on cells in small intestine

  • Absorption of nutrients

In female reproductive tract, cells have cilia

  • Transport oocytes and sperm

front 104

Simple columnar epithelium: small intestine

back 104

front 105

Pseudostratified columnar epithelium

back 105

  • Lines respiratory passages, epididymis, and vas deferens
  • Respiratory passages: motile cilia present
  • Goblet cells produce mucus that is transported by cilia to oral cavity (protection)
  • Male reproductive tract: nonmotile stereocilia present
  • Absorb fluid
  • Not all cells reach free surface, but ALL cells rest on basement membrane

front 106

Pseudostratified columnar ciliated epithelium

back 106

front 107

Transitional epithelium

back 107

  • Multiple cell layers
  • Changes shape
  • Relaxed state: stratified cuboidal with dome-shaped surface cells
  • Stretched state: stratified squamous with squamous-shaped surface cells
  • Lines calyxes, pelvis, ureter, and bladder of urinary system
  • Also called urothelium

front 108

Relaxed transitional epithelium: unstretched (empty) bladder

back 108

front 109

Stretched transitional epithelium: stretched (full) bladder

back 109

front 110

Stratified squamous epithelium

back 110

  • Multiple cell layers
  • Basal cells are cuboidal or columnar
  • Migrate to free surface and become squamous in shape
  • Nonkeratinized: living surface cells (protects from wear and tear)
  • Line moist cavities (mouth, pharynx, esophagus, vagina, and anal canal)
  • Keratinized: nonliving surface cells filled with keratin protein (protects from abrasion, desiccation, and bacterial invasion)
  • Line external surfaces of body
  • Layers called strata

front 111

Stratified squamous nonkeratinized: living surface cells

back 111

front 112

Stratified squamous keratinized: nonliving surface cells

back 112

front 113

Stratified squamous: Basal cell carcinoma

back 113

front 114

Stratified cuboidal (or columnar) epithelium

back 114

  • Two layers of cells
  • Surface cells cuboidal or columnar
  • Line larger excretory ducts of pancreas, salivary glands, and sweat glands
  • Withstands wear and tear

front 115

Stratified cuboidal epithelium: excretory duct of salivary gland

back 115

front 116

Pseudostratified columnar ciliated epithelium: note appearance of more than two rows of nuclei & cilia!

back 116

front 117

Glandular tissue

back 117

Exocrine glands: secrete products onto surface directly or through ducts

  • Secretion may be modified in the ducts

Endocrine glands: lack ducts; secrete into connective tissue--> bloodstream --> target cells; secretions are called hormones

front 118

Exocrine Gland Characteristics

back 118

front 119

Types of glands

back 119

front 120

Types of secretions

back 120

front 121

Types of secretions

back 121

Mucus: viscous secretion that lubricates or protects inner lining of organs; cells appear white or pale purple with H & E

  • Goblet cells
  • Sublingual salivary glands
  • Surface cells of stomach

front 122

Types of secretions

back 122

Serous: watery secretion often rich with enzymes; stain intensely with eosin (pink/red)

  • Acini of parotid glands
  • Acini of pancreas

front 123

Types of secretions

back 123

Mixed: mucus and serous secretory cells

  • Acini of submandibular glands

front 124

Exocrine ducts: epithelia

back 124

front 125

Classifying exocrine glands

back 125

Single cell vs. sheet of cells

Acinus vs. ducts

  • Describes where secretions are released vs. transported

Simple vs. compound

  • Describes complexity of duct branching

Alveolar (acinar) vs. tubular

  • Describes shape of duct ends where secretory acini are located

front 126

Unicellular exocrine glands

back 126

  • Single cells distributed among nonsecretory cells
  • Goblet cells (mucus secretion)

front 127

Multicellular exocrine glands

back 127

  • More than 1 cell
  • Subclassified based on arrangement of secretory cells (parenchyma) and branching of duct elements
  • Simplest is sheet of secretory cells at surface

front 128

  • Multicellular exocrine glands

Sebaceous gland

back 128

front 129

  • Multicellular exocrine glands

Mucus-secreting cells

lining the stomach

back 129

front 130

Simple tubular exocrine gland: large intestinal glands

back 130

front 131

Simple branched tubular exocrine gland: gastric glands

back 131

front 132

Simple coiled tubular exocrine gland: sweat glands

back 132

front 133

Compound acinar exocrine gland: mammary glands

back 133

front 134

Compound tubuloacinar gland: submandibular salivary gland

back 134

front 135

Endocrine glands

back 135

  • No ducts
  • Glands surrounded by capillary networks
  • Individual cells found in digestive organs
  • Endocrine tissue found in mixed glands that also have exocrine components
  • Pancreas and reproductive organs
  • Endocrine organs (typical hormone secreting glands)
  • Pituitary, thyroid, parathyroid, and adrenal glands

front 136

Mixed endocrine/exocrine gland: Pancreas

back 136

front 137

Mixed endocrine/exocrine gland: Pancreas

back 137