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Ocular Anatomy > Histology > Flashcards

Histology Flashcards

1
Q

What are the 7 steps for preparing a slide for light miscropy?

A
  1. ) Fixation
  2. )Dehydration
  3. ) Infiltration
  4. )Embedding
  5. ) Sectioning
  6. ) Staining
  7. ) Mounting
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2
Q

Describe fixation of a sample, the purpose and possible issues associated with this step.

A

Immobilize and cross link proteins to preserve sample using formalin, alcohol or freezing temperatures. Risks breakage or possible shrinking/swelling

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3
Q

Describe dehydration of a sample, the purpose and possible issues associated with this step.

A

Increase alcohol content of sample to avoid shrinkage. Risks breakage, possible shrinkage/swelling, possible removal of proteins/lipids

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4
Q

Describe infiltration of a sample, the purpose and possible issues associated with this step.

A

Volatile solvent (such as xylene) replaces alcohol b/c alcohol doesn’t mix with paraffin wax. Risks possible shrinkage/swelling or removal of proteins/lipids.

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5
Q

Describe embedding of a sample, the purpose and possible issues associated with this step.

A

Sample is EMBEDDED into molten paraffin wax to provide support to sample and allow for sectioning. Heat involved in this step could result in space b/t tissues

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6
Q

Describe sectioning of a sample, the purpose and possible issues associated with this step.

A

Sample is cut into 3-10 micrometer thick slices using microtome to allow for view of different layers of sample.Risks possible folds/scratches within the slices

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7
Q

Describe staining of a sample, the purpose and possible issues associated with this step.

A

Sample is exposed to dye (commonly use H&E) to create contrast amongst components. Risks over/under staining and false precipitates.

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8
Q

Describe mounting of a sample, the purpose and possible issues associated with this step.

A

Sample is fixated to a glass slide with a coverslip to allow viewing of sample in LM. Risks breakage of tissue or creating folds.

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9
Q

What are two other quick methods of preparing tissues and their use?

A
  1. Frozen sections-tissue immediately frozen and sectioned using a cryostat (cold microtome) allowing prep in minutes rather than days with other method, used for time critical instances (biopsy of an open operation pt)
  2. Smears-isolated cells are smeared directly onto slide and stained. Examples include blood, bone marrow and cervical cells (pap smear)
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10
Q

What is the most common stain used for tissues (for our purposes), what are its components and what color do those components stain/what structures?

A

H&E which is composed of Hematoxylin and Eosin

  • Hematoxylin stains blue and basophilic. It will stain organelles with lots of DNA/RNA [nucleus (heterochromatin, chromosomes, nucleoli), ribosomes in cytoplasm] and some secretory vesicles
  • Eosin stains red and acidophilic. Stains cytoplasm, mitochondria, some secretory/lysosomal cells, RBCs
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11
Q

What is the relationship between acidophilicity and basophilicity of a tissue slide and the living tissue?

A

There is no relationship, the trends that we recognize with prepared slides are based off a sampled that has gone through many steps of preparation and doesn’t reflect the acidophilicity/basophilicity of the living structure in biochemical surrounding

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12
Q

What are the three main components of the nucleus and descriptions of each?

A

Nuclear membrane-2 unit membrane containing nuclear pores (holes in membrane), continuous with RER of cytoplasm
Nucleolus-dense, central portion, the site of rRNA syn and initial ribosomal assembly
Chromatin-long tangled threads of DNA, RNA, assoc. proteins, become distinct entities during mitosis/meiosis (CHROMOSOMES)

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13
Q

What are the two interchangeable states of chromatin and the description of each?

A

Heterochromatin-tightly coiled and condensed, contains genomic info that is NOT transcriptionally nor metabolically active
Euchromatin- dispersed, extended; it is transcriptionally AND metabolically active

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14
Q

What is the importance of nuclear staining and the meaning/implications of a “light staining” or “dark staining” nucleus?

A

Size, shape, staining of nucleus helps in cell identification and functional activity

  • Light staining=euchromatic nucleus; it is large, well developed and transcriptionally/metabolically ACTIVE
  • Dark staining=heterochromatic nucleus; small, poorly developed nucleus and nucleolus, transcriptionally/metabolically INACTIVE (dead/dying cell will be intensely heterochromatic/pyknotic
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15
Q

What is the importance of the S phase?

A

Chromosomes are duplicated in preparation for mitosis; begins w 2 centrioles ends w 4 centrioles

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16
Q

What is karyotyping? What stage of mitosis are the cells suspended in for ideal results?

A

Visualization of the # and morphology of an individual’s chromosomes to screen for abnormalities. Colchicine is added to suspend the cells in metaphase (ideal for karyotyping)

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17
Q

What is a Barr body?

A

An inactivated X chromosome, used to sex type, XX (girl,), XY (boy). Girl will have Barr body. Remains condensed and transcriptionally inactive thru interphase

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18
Q

What are the divisions of the cell cycle?

A

Mitosis and interphase (G1, S, G2)
G1=most variable part of cycle, protein and RNA synthesis; grow and preform specialized Fox
S= DNA syn and proteins assoc. w chromatin
G2= synthesis of mitotic apparatus

19
Q

What is Go?

A

Outside of cell cycle can be cells that are temporarily non-dividing or terminal cells that will not divide

20
Q

What are the three cell categories and examples of each?

A
  • Constantly dividing labile cells (move rapidly thru the cell cycle) ex. Embryonic, skin, bone marrow
  • Quiescent stable Go, extended G1 that can re-enter cycle ex. Liver cells
  • Permanently non-dividing/permanent Go = postmiotic (heavily specialized/differentiated that can no longer replicate) ex. Neurons, cardiac and skeletal muscle
21
Q

What is the characterization and function of the cell membrane?

A

Semi-permeable phospholipid belayer b/t 7-10 nm thick, contains integral and peripheral proteins, allows for transport of material into and out of cell, maintain cell’s inner compositionn

22
Q

What is the function of cytoskeleton?

A

Support framework of cell, variety of proteins assembled into minute rods/filaments/tubules

23
Q

What are the two main cytoskeletal structure categories?

A

Filaments, Microtubules

24
Q

What are the different size categories of filaments?

A
  • Microfilaments/Thin/Actin filaments(~7nm)
  • Myosin Filaments (~12-16nm)
  • Intermediate filaments (~8-12nm)
25
Q

What are the main examples of microfilaments/Actin filaments and their function/location?

A
  • Microvili-fingerlike projection in epithelial tissue (intestinal tissue)
  • Cell junctions
  • Terminal web-network under apical surface of epithelial tissue containing microvili
  • contractile ring-responsible for cytoplasmic constriction during mitosis
26
Q

What is a location and example of myosin filaments?

A

In the sarcomere involved in muscle cell mov’t

27
Q

What is the primary function of intermediate filaments and a medical function?

A

Important in cell support/shape, they are stable with low cellular turnover
They are structurally specific for diff tissues therefore commonly used to identify origin of metastized cancer cells

28
Q

What are microtubules and common example of them?

A

Hollow tubes of tubulin (protein)

  • Centrioles: microtubule organization centers (9 triplets)
  • Mitotic spindle: attach/move chromosomes during cell replication
  • Cilia/flagella: motile projections (lungs, sperm), made of axoneme (extends thru shaft) and basal body (at base of cilia, similar in structure to a centriole)
29
Q

What’s the characterization/function of the mitochondria and how is it identified on a slide?

A

Composed of inner membrane, outer membrane and the cristae
Functions to produce ATP
It stains red; cells that are intended to produce a lot of ATP=lots of mitochondria=intensely red

30
Q

What are ribosomes, the two different kinds and what color do they stain?

A

Contain RNA from nucleolus, assemble amino acids into proteins, stains BLUE

  • Ribosomes associated w RER: assemble aa to secretory, lysosomal an integral membrane proteins
  • Free/polyribosomes: assemble proteins used for cell
31
Q

What is the RER and what does it stain/why?

A

Assembles proteins that need membrane enclosure/integral proteins
It stains blue due to attached ribosomes
Secretory cells/lysosomal cells will stain largely blue due to many SER/many ribosomes

32
Q

What is the SER and what does it stain?

A

Smooth ER, contains enzymes critical for lipid/cholesterol derived compounds

  • stains light/slightly red in cytoplasm
  • prominent in liver cells
  • well developed in secretory cells that specialize in lipids, lipoproteins and steroid hormones
  • sarcoplasmic reticulum in muscle cells = specialized SER
33
Q

What are the two terms describing mov’t in/out of cell?

A

Exocytosis: release material FROM cell
Endocytosis: bring material in via pinocystosis (to drink) or phagocytosis (to eat)

34
Q

What is the Golgi apparatus and its function?

A

Stack of flattened/membranous sacs
Chemical mod of proteins
Distro and recycling of various membranes of cell
Receives secretory & lysosomal proteins RER to prepare into vesicles for release

35
Q

What are secretory vesicles? What color due they stain? What is the effect on staining appearance?

A

Membrane bound sacs containing products for release
Stain red or blue depending on compound
Some cells release immediately-homogeneously stained (ex. Plasma cells)
Some cells store products= spotted cytoplasm (ex. Serous cells that secrete digestive enzymes)

36
Q

What are lysosomes? What are the various steps in the life of a lysosome?

A

“Bags” of hydrolytic enzymes, cells w many lysosomes are specialized to destroy
Primary lysosome: newly formed
Secondary lysosome: contain material to be destroyed
Residual bodies: contain leftover garbage to be exocytosed or will remain (lipofuscin)

37
Q

What are examples of lysosomal cells capable of destroying material that is outside the cell?

A

Eosinophils (disease fighting WBC) and osteoclasts (destroy bone)

38
Q

What are the terms describing the two methods of phagocytosis?

A

Heterophagy-substance originates from outside the cells (phagocytosed by cell then lysosome)
Autophagy-substance already present in cell (ex. Old organelle)

39
Q

What are some cytoplasmic inclusions and examples of them?

A

Stored foods: glycogen (sugar), lipid

Pigments: lipofuscin (residual bodies), melanin, carbon

40
Q

What are the three cellular adaptions we discussed and their meaning?

A

Atrophy: decrease in size/organelles
Hypertrophy: increase in size, organelles, fx
Hyperplasia: increase in cell # (cell must be able to replicate)

41
Q

What are the two terms describing cell death and their meanings?

A

Apoptosis: programmed cell death
Necrosis: death caused by injury (ischemia (lack of blood), mechanical injury, toxins, etc)

42
Q

What makes cytoplasm more acidophilic?

A

Red-staining
Mitochondria
Secretory vesicles
Lysosomes

43
Q

What makes a cytoplasm more basophilic?

A

Blue staining
Ribosomes (free or poly and SER)
Secretory vessicles

44
Q

What makes a cell appear empty?

A

Lipids, glycogen, mucus

Ocular Anatomy (3 decks)

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