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First Year Veterinary School > Histology- Exam #1 > Flashcards

Histology- Exam #1 Flashcards

1
Q

What is histology?

A

Science concerned with minute structure of cells tissues and organs in relation to their function.

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2
Q

What does fixation do?

A

Stops autolysis, prevents bacterial decompensation, stabilizes proteins

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3
Q

Is freezing used to fix samples?

A

Yes, but less frequently, freezing kills some cells and can leave artifact.

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4
Q

What kind of samples are usually fixed with freezing?

A

Nervous/ Adipose tissue

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5
Q

What occurs during processing?

A

Put in paraffin so it can be sliced thinly by microtome

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6
Q

What is staining based off of?

A

A variety of factors.

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7
Q

What kind of stains are there?

A
  • electrostatic charges ( Acid or basic( most) Neutral stains: methylene blue picrate( rare), indifferent (Sudan III and Sudan IV ( is scarlet red))
  • Supravital stains stain dead cells
  • Vital stains stain live cells ( vital stains must be done quickly because if tissue dies tissue will not stain. (Methylene blue is vital stain)
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8
Q

What is the most routine stain?

A

Hematoxyline & Eosin are the most routine.

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9
Q

What is hematoxyline and what is its features?

A

Hemotoxyline is basic and attaches to negative charges ( Nucleic acids are neg charged) (stains purple) Natural dye that comes from Haematoxylon Campechianum ( found in mexico)

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10
Q

What are other basic stains?

A
  • Toluidine blue ( mast cells)
  • Methylene blue (vital stain)
  • Fuscni Stains
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11
Q

What is eosin and some of its features?

A

Eosin is acidic and attaches to positive charges (Cytoplasmic structures are positively charged ( stains pink)

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12
Q

Acid stains what color in H+E?

A

PINK

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13
Q

Bases stain what color in H+E?

A

PURPLE

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14
Q

What are other acidic stains?

A
  • Orange G
  • Phyloxine
  • Aniline blue
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15
Q

What are some artifacts that can be present in samples?

A

Crystal artifact in liver tissue, from freezing, autolysis- from lack of staining.

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16
Q

What should you base a size estimate off of for an object in a slide?

A

On size of a red blood cell. Which is dependent on animal.

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17
Q

What is the approximate sizes of RBC in the chicken, frog, dog, and goat?

A

‣ Chicken: 9.5 microns
‣ Frog: 10-24
‣ Dog: 5 microns.
‣ Goat: 2.5 microns.

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18
Q

What is this stain? What is it used for?

A

Trichome stain ( Massons, Mallory, ect, colors depend on tissue/ cell type, ( skin is a good one for this )

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19
Q

What is this stain? What is it used for ?

A

Wright-Giemsa and Diff Quick (Good Cellular Stain, Cytology/ blood smear)

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20
Q

What is this stain? What is a good use for it ?

A

Orecin: Good for seeing wall thickness in cells

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21
Q

What is this stain? What is a good use for it ?

A

Toluidine Blue Specific for mast cells ( stain because of high concentration of negative charges found in heparin in the granules)

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22
Q

What is this stain? What is it used for ?

A

◦ Prussian Blue/ Perls Stain: Shows iron deposits (Iron stains blue). (Good stain to study hemochromatosis in liver cells of captive Mynah birds)

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23
Q

What is this stain? What is it used for?

A

◦ Congo Red (polarizer): Will stain amalloid bright green, too much amalloid is not good for you.

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24
Q

What is this stain? What is it used for?

A

◦ Gram staining: Bacteria stains purple based on if it gram positive or negative.

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25
Q

What is this stain? What is it used for?

A

◦ Ziegler Neelsen( acid Fast)- Tb is acid fast

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26
Q

What is this stain? What is it used for?

A

◦ Silver Stains ( GMS, Gomori, ect): Stains fungal wall black.

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27
Q

What kind of stain is this? What is this used for?

A

◦ Periodic Acid Schiff Stain (PAS): Stains sugars ( fungus stains pink) Can also stain polysaccharides in tissue ( Goblet cells stain dark because they are rich in polysaccharides)

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28
Q

What is electron microscopy? What are some reasons it is not used as much?

A
  • Higher resolution than light microscopy
  • Requires special training, equipment and is expensive so not used as much.
  • Fixatives are different then regular histology ( usually gold or other heavy metals) (Glutharaldehyde is most common)
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29
Q

What kinds of electron microscopy are there?

A
  • Scanning EM: 3D structure, due to electron deflection.
  • Transmission EM: 2D structure, goes through in one direction.
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30
Q

What is IHC?

A

Immuno Histo Chemistry
Target detection via Antibodies

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31
Q

In IHC, What are some important factors?

A
  • Ab-Ag bond is specific, both are proteins.
  • Immortal cells ( myeloma ( tumor of ab making cells)
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32
Q

What are Polyclonal antibodies? Monoclonal?

A
  • Polyclonal ab: multiple epitomes (can attach to multiple places)
  • Monoclonal Ab: single epitope (can attach to one place)
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33
Q

What are epitopes?

A

• Epitopes: part of protein that AB will attach to.

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34
Q

What is the difference between Direct IHC and Indirect IHC?

A
  • Direct IHC: Primary AB is tagged
  • Indirect: secondary ab ( targeting primary ab) is tagged ( secondary is flagged so you can see it)
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35
Q

What is the counter stain for IHC?

A

Hematoxylin

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36
Q

What is In situ hybridization?

A
  • PCR: Amplification of DNA so you can detect/ see it. Can be done in real time. Specific to that sequence
  • Usually more specific
  • Ex: Mycoplasmosis is smallest self replicating prokaryote, and has sunny side egg colony
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37
Q

What is the process for cytologies? What types are there?

A
  • Dry and stain, fixing is optional
  • Various types: impression smears, fine needle aspirate, cytosine
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38
Q

Who coined the term Cell, and when?

A

• Robert Hooke in 1665 coins term “cell”

39
Q

What is cell theory and who are the individuals associated with its start?

A

• Schwan and Shleiden in 1838 “ cellular theory”
◦ Cell is the smallest living stucture
◦ Organ functions are the collective result of the functions of its constituting cells

40
Q

Who introduced cellular pathology? What is it?

A

• Virchow in 1858 “cellular pathology”
◦ An organs disease is the result of the disease in its constituting cells.
◦ A cell originates from another cell.

41
Q

What makes you alive?

A

◦ Irritability: ability to detect/ respond to stimulus (inflammatory cells/ neutrophils)
◦ Conductability: Conduct stimulus (neuron)
◦ Contractibilty: Abilty to change shape
◦ Absorption: introduce materials into cell. May be through Phagocytosis (solids or pinocytosis)
◦ Secretion: Release of useful products (Goblet Cells- produce mucus)
◦ Excretion: Release of waste
◦ Assimilation: Construction of new cellular elements
◦ Growth: Increase in cellular mass keeping the nuclear cytoplasm ration
◦ Reproduction: produce daughter cell while transferring genetic material. (Ova and sperm)

42
Q

What is the cytoplasm of a cell?

A

• Cytoplasm:everything within a cell
◦ Cytosol: Medium inside limits of cell where organelles are located
◦ Cytosol and organelles

43
Q

What is the plasma membrane of a cell?

A

• Plasma Membrane
◦ Limits: Cell ( exomembrane), Organelles and Nucleus (endomembranes), Mitochondrial Core ( internal( mitochondrial) membrane), Border of cells
◦ Chemistry: Protiens: Structureal involved in signaling/ transportation, Lipids: mainly phospholipids, and cholesterol, Hydrocarbons: mainly + protiens (surface glycoproteins), Glycoprotiens, Glycolipids,ect.
◦ Important membranes: micovilli (apical border)(brush border, increases surface area for cell increasing absorption), Glycocalix (endothelium, keeps cells from sticking to lumen) , Intermembranous junctions (desmosomes : looks like Velcro, helps hold cells in placed) .

44
Q

What is mitochondria?

A

• Mitochondria: important for energy production
◦ Structure: Outer smooth membrane, matrix, inner rough membrane/ crests
◦ Main Functions: Oxidative phosphorylation (ADP to ATP), Respiratory chain, Krebs cycle.
◦ Autonomous division (binary fission)
◦ Absent in prokaryotes.

45
Q

What is the Endoplasmic Reticulum?

A

• Endoplasmic Reticulum: Smooth and Rough (found throughout cytosol)
◦ Rough ER: surface covered with ribosomes, protein synthesis, forms nuclear membrane
◦ Smooth ER: Surface lacks ribosomes, produces enzymes for lipid synthesis/ metabolism (steroid hormone synthesis, glycogen metabolism)

46
Q

What is the golgi apparatus?

A

• Golgi apparatus: Connects ER and cell membrane
◦ Produces polysaccharides, stores products from SER and RER, Forms zymogen granules and other vesicles to export golgi, RER, and SER products. These granules merge with cell membranes, contents are then extruded via exocytosis. Source of lysosomes.

47
Q

What are lysozomes?

A

• Lysosomes: are numerous in immune system cells, neutrophils, Natural Killer Cells, ect. Renal tubular epithelium. Toduline blue can also stain lysosomes.

48
Q

What is the cytoskeleton?

A

• Cytoskeleton: Structure, transport, movement. Microtubules are made of tubulin protein. Centriole is responsible for cell reproduction, mitosis spindle, and is base for cilia, flagella. (9 groups of 3) Microfilaments (intermediate filaments) ex:actin, myosin, vimentin, cytokeratin.

49
Q

What is the steps of cellular division?

A

S( Ready for mitosis)——> G2 (Getting Scaffolding)——> M (Mitosis (prophase, metaphase, anaphase, telophase)) ——> G1 ( Function/ Growth) ——> Back to S to repeat cycle.

50
Q

What is the difference between mitosis and meiosis?

A

Mitosis: cell division
Meiosis: cell division and unification of daughter cells. Gametes are the result

51
Q

What is Gametogenisis?

A

Gametogenisis: Development of Gametes

52
Q

What is spermatogenesis?

A
  • Begins with sexual maturity, undifferentiated epithelium into sertoli cells which support spermatogonia. - Stem cells decide and create Spermatogonia A and B (A will go back and produce more, while be will go through meiosis)
53
Q

When do spermatids become spermatozoa?

A

When nucleus condenses into head, golgi acrosomic granules surround nucleus, centrioles to mid piece, mitochondria surround centrioles, cytosol and other organelles removed in residual body

54
Q

What is Oogenesis? When does it begin?

A

◦ Oogenesis: Begins in utero, some die when undergoing mitosis, others differentiate. Squamous cells surround 1a oocytes (primordial follicle). At sexual maturity 1a completes division and becomes 2a oocyte which then divides. Fertilization is needed to complete meiosis II.

55
Q

What stage does oogenesis remain in in foxes, horses, and dogs? When will it leave this stage?

A

Prophase I until fertilization

56
Q

What is fertilization?

A

Oocyte + Spermatozoon = Zygote

57
Q

What are the steps to fertilization?

A

• Spermatozoon breaks through oocytes corona radiata. Zona pelluicida is breached by sperm who will fertilize egg. Zona pelluicida will then alter to repel other sperm. 2 haploid cells become 1 diploid cell.
- Spermatozoids deposited in vagina or uterus: they are protected by seminal secretions (protects from pH in vagina/uterus). They stop acrosome activity until in the right position) uterine tube.

58
Q

What is spermatazoa capacitation?

A

Loss of surface cholesterol and glycoprotiens, spermatozoon and acrosome membranes fuse.

59
Q

What are the chromosome combinations for sex determination in animals? Mammals and birds.

A

Sex determination: XX (female) and XY (male) in mammals. Birds: ZW (Female) ZZ ( Male)

60
Q

What occurs during cleavage/ segmentation in the growth phases?

A

Zygote divides int blastomeres ( mitosis) They become a sphere: Morula: Which differentiates into trophoblast (placenta) and Embryoblast ( embryo). Morula migrates to uterine body, keeping Zona pelluicida. Fluid fills cavity and becomes blatocele, Blastocyst formation is end.

61
Q

What occurs during gastrulation in the growth phases?

A

Embryoblasts goes from collection of cells to 3 tissue types. (Ectoderm ( outside of blastocyst) , Endoderm ( inside of blastocyst), Mesoderm (middle)
◦ Ectoderm: Primitive node, Primative groove ( Notochord= end of gastrulation)
‣ Primitive streak differentiates to cranial/ caudal ends, and elongates.

62
Q

What are some important parts of Body shape aquisition? What is Neurulation

A

Body Shape Acquisition: Sketches all organs, Gene regulatory networks
◦ Includes Neurulation (formation of neural plate, groove, and tube ( which will form CNS) as well as Neural crest cells ( which will form PNS and adrenal glands)

63
Q

What is Mesodermal differentiation?

A

◦ Mesodermal Differentiation:
‣ Paraxial Mesoderm: Includes Somitomeres ( cranial structures) and Somites( Axial Skeleton: Dorsal vertebrae, muscles, and dermis)
‣ Intermediate Mesoderm: Mesonephros (Urinary and reproductive organs)
‣ Lateral Mesoderm: Somatopleure ( Thorax, abdomen, structures, and mesothelium) and Splachnopleure ( epithelium and connective tissues: respiratory, digestive, thyroid, parathyroid.)

64
Q

What is somatopleural tubulation?

A

◦ Somatopleural tubulation: Endoderm ( This is the folding or tubulation of spomatopleure (Outter), and splachnopleure ( inner). Cranio- caudal folding and lateral folding (fourth week of development.

65
Q

What is trilaminar embryo

A

◦ Trilaminar embryoL Cordon of cells from primitive node in mesoderm: Notochord. THis makes embryo symmetrical, induces formation of neuroectoderm, forms intervertebral discs much later

66
Q

Where does epithelium originate from?

A

Ecto, Mesoderm and endoderm

67
Q

Where does musculoskeletal tissue originate from?

A

Mesoderm

68
Q

Where does connective tissue originate from?

A

Mesoderm

69
Q

Where does Nervous tissue originate from?

A

Ectoderm

70
Q

How does signaling occur? What are the outcomes?

A

Paracrine, Direct Contact, Autocrine, synaptic, endocrine
◦ Outcomes: Division, differentiation, shape changes, apoptosis.

71
Q

What is the architecture of muscle?

A

The sarcomere: Myofilaments and Sarcoplasmic reticulum full of calcium. Actin (light), Myosin(dark), and troponin, tropomyosis (Myofilaments) Sliding of myofilaments = contraction = movement

72
Q

What are the 3 types of muscle cells and their characteristics?

A
  • Skeletal: Striated, voluntary, nucleus in periphery’s long and multi nucleated. Rich in myoglobin ( storage of O2, found alot in skeletal muscle of marine mammals) (Has z bands, A and I bands) (strong quick, discontinuous voluntary contraction)
  • Cardiac: Striated, involuntary, intercalated disks ( helps with coordinated contraction) Single central nucleus, rich in glycogen, continuous short contractions.
  • Smooth: Non striated, involuntary, fusiform, irregular shape, single nucleus in center. Lowest concentration of myoglobin and glycogen. Myosin, Actin, Tropomyosin, calcium and calmodulin causes contraction. Bunches together when contracted. Weak, slow contraction.
  • Troponin: cardiac cell death causes excess to be released into blood stream, which is why troponin is high when cardiac necrosis.
73
Q

What is bone?

A

rigid but dynamic organs which build endoskeleton of vertebrates.

74
Q

What is the components of bone tissue?

A

Level 1: 3 components of bone tissue : Organic: collagen type I (90%) Non collagenous proteins (10%), Mineral : Hydroxypatite, and Water
Level 2: Mineralized Collagen fibril: bone basic building block

75
Q

What is the function of bone tissue? What are the layers?

A

Mechanical support, weight bearing, muscle attachment sites, protection of vital structures, hemopoiesis, mineral homeostasis ( mostly calcium and phosphate)
Periosteum: external membrane, continues with tendons
- Outer layer: connective tissue
- Inner layer: osteopenia layer
Sharpeys Fibers: bundles of Type one collagen fibers connecting periosteum to bone

76
Q

Where do bone cells originate from?

A

Mesenchymal stem- cell line

Hematopoietic stem cell line

77
Q

What are osteoblasts? Osteocytes?

A

Osteoblasts (active deposit) :Lines bones surfaces, cytoplasmic processes to contact with osteocytes, secrete osteoid: unmineralized, organic bone material ( mostly collagen type -1) Osteoid is typically deposited in 3-4 um layers called lamella. Later osteoblasts also take place in inducing mineralization. Follow 1 of 3 courses: disappear ( apoptosis?), become quiescence, embedding themselves within osteoid and become osteocytes. Mature osteoblasts are imprisioned in the bone matrix in lacunae. More than 90 % of bone cells Half life’s are decades.

  • Bone lining cells (quiescence)
  • Osteocytes ( mature osteoblasts) : Number per area dependent on species. (Increased in smaller species) Serve as bone nervous system. Bones protecting vital organs wont necessarily follow this. Osteocytes induce addition and removal of bone. Remodeling usually occurs at night. They also induce replacing “dead” bone. Resorb mineralized bone from bones surface (Howships Lacuna) or within ( cutting cone)
78
Q

What are osteoclast?

A

Osteoclasts (active absorption)

79
Q

What is the cell lines of Osteoblasts, Osteocytes, Osteoclasts?

A

Osteoblasts/ Osteocytes - Mesenchymal

Osteoclasts: Hematopoietic

80
Q

What are the processes of bone formation?

A

Ossification or Osteogenesis

81
Q

What are the two types of ossification?

A

Intramembranous ossification: mesenchyme -> Bone (direct transition) Formation of flat bones, also essential during healing of bone fractures
Endochondral Ossification: Mesenchyme -> cartilage anlage -> bone (Bone becomes cartilage first) Bone develops from preexisting hyaline cartilage model. Most long short and irregular process bones. Ends at puberty, when growth plates fuse leaving epiphysial line. Hormones and O2 determine cells created. Not uncommon that epiphysis are still cartilage when neonatal/ young. Which predisposes young animals to fracture.

82
Q

What is bone modeling? Remodeling?

A

• Bone modeling: Osteoblasts and osteoclasts work independently of one another. Bone remodeling: Osteoclasts remove bone, and osteoblasts deposit new bone to replace it. Coupled in remodeling. Secondary osteons and trabecular packets are surrounded by a cement line ( reversal line)and they stop progress of micro cracks. The interstitial lamellae are remnants of older osteons

83
Q

What are the different types of bones?

A

• Cortical/ trabecular bone:
Compact: outer shell surface
Trabecular Bone: lies within cortical shell ( spongy bone)
• Woven Bone: Primary bone tissue, loosely packed, purely oriented mineralized collagen fibrils. Laid down rapidly and randomly, and are later replaced with lamellar bone via remodeling. Most common in young animals (large mammals), fracture callus’, and some bone tumors ( osteosarcoma)
• Fibrolamellar bone: Primary bone tissue, found in larger and rapidly growing mammals. (Varies between animals)
• Circumferential lamellar bone (CBL): Primary bone tissue, concentric lamellae under periosteum/ endosteum. Less vascularized and remodels into secondary osteons. Repeat every year (tree rings) Most reptiles long bones.
• Havarsian bone: secondary bone tissue, replaces older bones, concentric lamellae, blood vessel in center, run parallel to long axis of bone, cement line around osteon. Volkmanns cannals run between osteons and connecting to periosteum and endosteum.
• Trabecular Packet: Remodel almost exclusively on bone surface. Inner part constantly increases in mineral content. Packets 1-2 superficial (extend to bone surface), 3-6 are deep ( encapsulated by cement lines)

84
Q

What is cartilage? What is its origin?

A

• connective tissue, mesenchyme origin, a vascular , nutrients/ metabolic waste via diffusion. Cartilage functions but tensile and compressive strength. It is flexible and resilient and is structural support for soft tissues. Distributes and dissipates stresses.

85
Q

What are some important components of cartilage?

A

• Abundant extra cellular matrix . When stained it is separable into pale ( interterritorial matrix, low GAG (Sulfated Glycosamino glycans) and darkly (territorial matrix, high GAG) areas.

86
Q

What are chrondroblasts? Perichondrium?

A

Chondroblasts: reside in perichondrium and produce extracellular matrix. Chondroblasts are trapped in extracellular matrix ( in lacunae) and mature into chondrocytes.
Perichondrium: Layer of vascularized, dense, irregular connective tissue that surrounds hyaline and elastic cartilage. Outer fiberous layer includes type 1 collagen fibers, fibroblasts, blood vessels, and nerves. Inner chondrogenic layer contains undifferentiated mesenchymal cells, which differentiate into chondroblasts that decree the external cartilage matrix.

87
Q

What are some cartilage types?

A

Articulate hyaline cartilage and fibrocartilage lacks perichondrium.
Hyaline: Most common, forms most of developing skeleton, type II and type III Collagen fibers. Firm but flexible, may calcify with age.

Elastic Cartolage: very flexible: Found in epiglottis, larynx, ear pinnacle, auditory tube.

Fibrocartilage: Alternating layers of hyaline cartilage matrix and dense connective tissue fibers( type - 1 collagen) and is oriented in the direction of stress. Provides tensile and compressive strength and resists deformation. Lacks perichondrium.
Will be found in intervertebral discs, meniscus, pelvis/ pubic symphysis since their is a lot of tension and compression. Formed via tissue deposition and invasion of chondroblasts.

88
Q

What are some important cartilage parts?

A

Grove of ranvier: Contributes chondrocytes to the growth plate for the growth in diameter. Competes with growth, prone to damage.
Ring of LaCroix: Provides mechanical support for the weak bone, cartilage interface of the growth plate. Supports Groove of Ranvier ( its like a girdle)
Cycle causes the reserve cartilage toward epiphysis and bone elongates. When reserve cartilage is depleted the bone stops elongating and growth plate is fused. Rodents: Growth plate never fuses, but not rapid growth, they continue to grow for their entire lives (very little)

89
Q

What are the parts of the hayline cartilage growth plate?

A
  1. ) Reserve cartliage zone
  2. ) Cell proliferation zone
  3. ) Maturation/ hypertrophic zone
  4. ) Calcification zone
  5. ) Bone deposition zone
90
Q

What are the general characteristics of epithelial tissue?

A

Regenerative with some cellular plasticity, built onto basement membrane, avascular( dependent on underlying connective tissue) Apical border may have cilia, microvilli, or stereocilla. Little intercellular matrix, joined by intercellular links.
Keratinization: Upper layer of dead cells, firmly attached, provide impermeable flexibility to minimize dehydration. Also covers wet surfaces subject to abrasion.
Intercellular links/ junctions: Tight Junctions ( Zona occludens, columnar cells, ex intestinal mucosa)), Terminal Bars (Zona adherens, less tight, cuboidal and columnar epithelia), Desmosomes ( macula adhaerens, intracellular bridges, spiny appearance, squamous epithelium of epidermis, mostly), and gap junctions( connections between cytoplasm of two cells, cuboidal epithelium. (Most cells have at least 2-3 junctions if not all of them)

91
Q

What are the characteristics for exocrine glands? What are the secretion methods? Secretion Types?

A

exocrine: opens to surface (tubular compound ( upside down tree), unicellular (alone and small), Simple tubular ( long and solo), Simple alveolar (single and rounded), alveolar compound (rounded, multiples, tree like)
- Secretion methods
• Merocrine: release via exocytosis, cytoplasm intact
• Holocrine: secretion is terminal, cells disintegrate (cell is dead once all contents are gone)
• Apocrine: membrane bound bless of cytoplasm.
‣ Secretion Types:
• Mucins (glycosylated proteins) lubrication/ protection ( goblet cells)
• Serous Secretion: Protiens ( non- glycosylated) (ex: digestive enzymes, pancreas exocrine portion)
• Seromucous glands: Combination of digestive enzymes and mucus (ex salivary gland)

92
Q

What is the characteristics of endocrine glands?

A

endocrine: under skin. (Follicular cells and ribbon)

93
Q

Why do we care about epithelia?

A

Epithelia cover all surfaces, working as protectors and connectors. Epithelia also become specialized substance- producing structures (glands)

First Year Veterinary School (43 decks)

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