Practical 1 Histology

Question 1

How are specimens prepared for microscopic examination? What are they fixed with first?

Answer 1

Most tissue slices are thinner than a cell (2-10 micrometres) and are fixed, embedded, sliced and stained.
Fixed with formalin (aqueous solution of formaldehyde) which prevents rotting and cross links cell constituents rendering them insoluble and preserving them.

Question 2

What are they embedded with?
How is the wax removed and dehydrated?
What cell constituents are removed during this process?

Answer 2

Paraffin which extracts water, then is mounted onto the slide and stained.
Using an organic solvent before rehydrated through increasing dilutions of alcohol in water.
Lipids- major components of cell membranes and adipose(fatty) acids.

Question 3

Creating thin specimens poses what issue?

Answer 3

Dimension reduction- 3D objects reduced to 2D images

Question 4

Alcian blue stains what structures blue?

Answer 4

GAG-rich structures, mucous goblet cells, mast cell granules and cartilage matrix.

Question 5

Eosin stains colloidal proteins (e.g. plasma) what colour?

It stains keratin what colour?

Answer 5

Pink

Orange/red.

Question 6

What colour does iron haemotoxylin stain nuclei and elastic fibres?

Answer 6

Black

Question 7

Haemotoxylin stains nuclei and RNA what colour?

Answer 7

Blue.

Question 8

Periodic Acid Schiff colours what structures magenta?

Answer 8

Hexose sugars, goblet cell mucins, cartilage matrix, glycogen, basement membranes and glycocalyx.

Question 9

Perl’s stain stains ferric iron what colour?

Answer 9

Prussian blue.

Question 10

Romanovsky Stains stains what 3 structures purple?
What 2 structures a red/ pink colour?
What 2 structures a pale blue colour?
What structure a dark blue/ purple colour?

Answer 10

Chromatin, azurophils and neutrophil granules.
Erthrocytes and eosinophil granules
Lymphocyte and monocyte cytoplasm
Basophil granules.

Question 11

Toulidine blue colours what 3 structures a dark blue?
What structure a pale blue?
What 2 structures a bright purple?

Answer 11

Nuclei, ribosomes and cytoplasm
Cartilage matrix
Mast cell granules and GAG-rich components

Question 12

Van Gieson’s trichrome stains colours collagen what colour? Cell cytoplasm what colour? Nuclei what colour?

Answer 12

Pink/ red
Yellow/ olive green
Black.

Question 13

Role of epithelial tissues? Role of supporting tissues?

Role of muscle cells? Role of nerve cells? Role of germ cells?

Answer 13

Protection, absorption, secretion- enzymes, hormones etc.
Soft and hard skeletal tissues- bone, cartilage etc.
Contraction and locomotion. Communication. Reproduction.

Question 14

Small cells have a diameter of about what? Why do lymphocytes have little cytoplasm?
Large cells have a diameter of about what?

Answer 14

10 micrometres e.g. lymphocytes- are less metabolically active and when activated increase their cytoplasm.
100 micrometres e.g. nerve cells with axons up to 1 metre.

Question 15

What are the 6 shapes of cells?

Answer 15

Rounded, polygonal- squashed and irregular shapes, fusiform- spindle shaped, squamous- flattened plates, cuboidal- square in 2D and columnar- taller than they are wide.

Question 16

How big are dormant cells compared to metabolically active ones?

Answer 16

Smaller.

Question 17

How long do cells lining the gut live for? Tissues- blood, skin, connective tissue? Bones and tendons? Skeletal muscle? Nerves, brain, cardiac and germ cells?

Answer 17

Days. Months- erthyrocytes= 120 days. Years. Nearly whole life. Whole life.

Question 18

Which type of chromatin is darker compared to euchromatin?

Answer 18

Heterochromatin- is transcriptionally inactive.

Question 19

In what cells is the Golgi apparatus prominent? What is this known as? 3 types of Golgi apparatus?

Answer 19

Plasma cells- euchromatin and heterochromatin= ‘clock face’ pattern. Perinuclear Hoff. Cis face- nuclear facing, receives vesicles from smooth ER, phosphorylates some proteins. Trans Golgi- proteolysis, packs macromolecules into vesicles which bud to the surface. Medial Golgi- central forming complex oligosaccharides by adding sugars to lipids and proteins.

Question 20

Types of vesicles?

Answer 20

Cell-surface pinocytotic/ phagocytotic, Golgi-derived, ER-derived, lysosomes(degrades proteins,) peroxisomes(H+-ATPase on membrane creates low internal pH to oxidise long-chain fatty acids.)

Question 21

3 forms of the cytoskeleton organelle? Diameter? Where found and what made of?

Answer 21

Microfilaments- 5nm diameter, made of actin, G-actin= globular polymerises into filamentous F-actin= bracing mesh(cell cortex) on inner surface of cell membrane.
Intermediate- 10nm, 6 types anchored to transmembrane proteins.
Microtubules- 25nm, tubulin proteins, found in all cells apart from erythrocytes, Alpha and Beta arrange in groups of 13 to form hollow tubes.

Question 22

6 types of intermediate filaments and location of each?

Answer 22

Cytokeratins- epithelial cells, desmin- myocytes, glial fibrillary acidic protein- astrocytes, neurofilament protein- in neurons, nuclear laminin- nuclei of all cells and vimentin- mesodermal cells.

Question 23

What is lipofuscin?

Answer 23

A membrane-bound orange-brown pigment, derived from per oxidation of lipids in older cells and is common in the heart and liver.

Question 24

What and where are lipids found as?

Answer 24

Non-membrane vacuoles that are empty space and are found in adipocytes and the liver.

Question 25

What and where is glycogen found as?

Answer 25

Polymer in the cytoplasm normally seen on electron microscopy and accumulates in some cells and due to some diseases.

Question 26

What 2 things can tissue be composed of?

Answer 26

Interstitial fluid- water, salts in solution, peptides and proteins.
Extracellular material- fibrillar proteins e.g. tendons, glycosaminoglycan jelly, inorganic salts as solids e.g. calcium in bone.

Question 27

What is cytology?

Answer 27

The analysis of the fine structure of cells by light microscopy.

Question 28

What are simple tissues?

Answer 28

Assembly of cells in specific fashion where all cells are of same structure/ mixture of cells with different functions e.g. nervous tissue= neurons, astrocytes, microglia(immune cells) and ependyma(epithelial cells.)

Question 29

What is systems histology?

Answer 29

The study of the arrangement of different tissues at the microscopic level.

Question 30

What are the 4 types of cells?

Answer 30

Empirical- van Giesons and trichrome. Histochemical- chemical reaction between specific tissue components and component of stain e.g. PAS. Immunohistochemical- antibodies applied to specific cell constituents to visualise details at light microscopic level.

Question 31

The nuclei of cancer cells display what type of shape and chromatin?

Answer 31

Large nuclei which vary in shape and size= nuclear pleomorphism and nuclear hyperchromatism.

Question 32

What is crinophagy?

Answer 32

Unwanted product in secretory vesicles is destroyed by direct fusion of secretory vesicles with lysosomes.