CSMLS REVIEW
HISTOLOGY
QUESTIONS AND
ANSWERS LATEST
TOP SCORE.
Grossing CORRECT ANSWER.described tissues (size, weight, colour)
Large tissue take section (want outer edge of bad and some normal, and
lymph nodes) small tissue do whole thing
Put in formalin to start to fix
Immunoflourescent studies not fixed
Brain fixed several days before being grossed (large container) via circle
of willis avoid cone head artifact (big enough container req)
Uterus (cut open and then
fixed) cervix is of concern and
fibroids
Masectomy prolonged fixation
lung inflated with formalin
Hematology = mercury fixative
(spleen) sliced first (capsule slows
fixation)
,Dictation of what is in each cassette
Fixation Delay CORRECT ANSWER.If not done properly cannot be
corrected Goal is to preserve morphology
,If delayed
- cell swelling (larger), due to osmotic balance water accumulated
- glassy cytoplasm (clearer), glycogen is used up
-Eosinophilia: use of glycogen = lactic acid, lower pH, denature proteins,
increase pos, increase eosin, organelles (RER) broken down decreased Hx
- Surface changes: low pH denature filaments, lose cell attachments
(Desmosomes), desquamation (CHAOS)
- Nuclear changes: lysosomes need exact pH to keep enzymes inactive
(need E), when gone enzymes active = nuclease
Karyolysis: Chromatin fades
Pyknosis: nucleus shrinks and
dark Karyorrhexis: Fragment
nucleus
Putrefaction: bacteria proliferate, enzymes damage
tissues Autolysis: damage tissue no nuclei
Types of fixatives CORRECT ANSWER.Chemical
- change protein shape (denature) inactive enzymes
Picric acid, formaldehyde, mercuric chloride, dichromate, osmium tetroxide,
zinc salts, alcohol
Physical
- heat removes water, changing shape inactive enzymes
Air dried (heme
malignancy) post fixed
with methanol
Coating fixatives = spray covers
Fluid specimens
- centrifuge and then smear
Chemical Fixative details (coagulant) CORRECT ANSWER.Coagulant fixatives (type
of chemical)
Alcohol (smears)
Acetic acid(w/others)inc nuclear
detail Acetone= fix frozen sections
Mercury (not used alone=
compound) enhanced nuclear
staining (hematology) toxic and
corrosive
ARTIFACT black pigment (not around blood - like formalin pigment,
****remove with lugol's iodine and sodium thiosulphate)
Zinc sulfate
, safer 3than 3mercury
Ag 3preservation, 3stabilizes 3protein 3conformation 3(histidine 3and 3cysteine)
Picric 3acid 3(phenol)
3(coagulation/additive) 3also 3a 3stain
fix 3with 3alcohol 3after 3(keeps 3salt 3picrates 3that 3are 3formed)
*** 3explosive 3when 3dry
improved 3staining 3with 3anionic 3dyes 3bc 3acid
has 3yellow 3colour 3removed 3with 3washing 3in 3high 3pH
Aldehyde 3Fixatives 3CORRECT 3ANSWER.Non-coagulant
3Formalin 3and 3glutaraldehyde
formaldehyde 3= 3gas-> 3saturated 3= 3aqueous
3formalin 3100% 3used 3at 310% 3formalin 33.7%
3formaldehyde
slow 3at 3acidic, 3fast 3in 3alkaline 3***
paraformaldehyde 3= 3precipitate 3polymer 3white 3( 3leads 3to 3ineffective
3fixation) 3some 3methanol 3can 3prevent
Formalin 3pigment
Spontaneous 3oxidation= 3formic 3acid 3lower 3pH
in 3bloody 3tissues 3(when 3hgb 3breaks 3into 3acid
3hematein) 3prevented 3by 3buffering 3or 3make 3fresh
** 3Remove 3with 3alcoholic 3picric 3acid
Formalin 3penetrates 3fast 3but 3fixes 3slow 3(24 3hr 3(can 3start 3with 3formalin
3and 3finish 3in 3alcohol 3to 3speed 3up)
glutaraldehyde 3fixation
- larger, 3slower 3penetration
- leaves 3free 3eldehyde 3(false
3PAS 3+) 3ox 3quickly 3(keep
3sealed)
for 3electron 3microscopy 3(harder, 3more 3links 3= 3ultrastructure
3preserved) 3fixes 3<2 3hours
Mechanism 3of 3fixation 3CORRECT 3ANSWER.1) 3formalin 3bind 3functional 3group
3and 3add 3CH2OH 3(temporary, 3can 3be 3washed 3away) 3adding 3OH 3group 3=
3hemiacetal
2) 3methylene 3bridge 3formation 3= 3link 3functional 3groups 3via 3OH
3(24hr 3to 3form) 3not 3easily 3reverse
Effects 3of 3fixation 3CORRECT 3ANSWER.Less 3eosin/anionic 3staining
1) methylene 3bridges 3and 3hemiacetal 3involves 3amino 3groups 3(cationic) 3(less
3stained)
= 3eosin 3(anionic) 3staining 3reduced
2) aminos 3not 3near 3others 3= 3only 3hemiacetal 3no 3bridge
these 3oxidized 3to 3carboxylic 3acid 3residues 3(neg) 3increased 3neg 3decreased 3eosin
HISTOLOGY
QUESTIONS AND
ANSWERS LATEST
TOP SCORE.
Grossing CORRECT ANSWER.described tissues (size, weight, colour)
Large tissue take section (want outer edge of bad and some normal, and
lymph nodes) small tissue do whole thing
Put in formalin to start to fix
Immunoflourescent studies not fixed
Brain fixed several days before being grossed (large container) via circle
of willis avoid cone head artifact (big enough container req)
Uterus (cut open and then
fixed) cervix is of concern and
fibroids
Masectomy prolonged fixation
lung inflated with formalin
Hematology = mercury fixative
(spleen) sliced first (capsule slows
fixation)
,Dictation of what is in each cassette
Fixation Delay CORRECT ANSWER.If not done properly cannot be
corrected Goal is to preserve morphology
,If delayed
- cell swelling (larger), due to osmotic balance water accumulated
- glassy cytoplasm (clearer), glycogen is used up
-Eosinophilia: use of glycogen = lactic acid, lower pH, denature proteins,
increase pos, increase eosin, organelles (RER) broken down decreased Hx
- Surface changes: low pH denature filaments, lose cell attachments
(Desmosomes), desquamation (CHAOS)
- Nuclear changes: lysosomes need exact pH to keep enzymes inactive
(need E), when gone enzymes active = nuclease
Karyolysis: Chromatin fades
Pyknosis: nucleus shrinks and
dark Karyorrhexis: Fragment
nucleus
Putrefaction: bacteria proliferate, enzymes damage
tissues Autolysis: damage tissue no nuclei
Types of fixatives CORRECT ANSWER.Chemical
- change protein shape (denature) inactive enzymes
Picric acid, formaldehyde, mercuric chloride, dichromate, osmium tetroxide,
zinc salts, alcohol
Physical
- heat removes water, changing shape inactive enzymes
Air dried (heme
malignancy) post fixed
with methanol
Coating fixatives = spray covers
Fluid specimens
- centrifuge and then smear
Chemical Fixative details (coagulant) CORRECT ANSWER.Coagulant fixatives (type
of chemical)
Alcohol (smears)
Acetic acid(w/others)inc nuclear
detail Acetone= fix frozen sections
Mercury (not used alone=
compound) enhanced nuclear
staining (hematology) toxic and
corrosive
ARTIFACT black pigment (not around blood - like formalin pigment,
****remove with lugol's iodine and sodium thiosulphate)
Zinc sulfate
, safer 3than 3mercury
Ag 3preservation, 3stabilizes 3protein 3conformation 3(histidine 3and 3cysteine)
Picric 3acid 3(phenol)
3(coagulation/additive) 3also 3a 3stain
fix 3with 3alcohol 3after 3(keeps 3salt 3picrates 3that 3are 3formed)
*** 3explosive 3when 3dry
improved 3staining 3with 3anionic 3dyes 3bc 3acid
has 3yellow 3colour 3removed 3with 3washing 3in 3high 3pH
Aldehyde 3Fixatives 3CORRECT 3ANSWER.Non-coagulant
3Formalin 3and 3glutaraldehyde
formaldehyde 3= 3gas-> 3saturated 3= 3aqueous
3formalin 3100% 3used 3at 310% 3formalin 33.7%
3formaldehyde
slow 3at 3acidic, 3fast 3in 3alkaline 3***
paraformaldehyde 3= 3precipitate 3polymer 3white 3( 3leads 3to 3ineffective
3fixation) 3some 3methanol 3can 3prevent
Formalin 3pigment
Spontaneous 3oxidation= 3formic 3acid 3lower 3pH
in 3bloody 3tissues 3(when 3hgb 3breaks 3into 3acid
3hematein) 3prevented 3by 3buffering 3or 3make 3fresh
** 3Remove 3with 3alcoholic 3picric 3acid
Formalin 3penetrates 3fast 3but 3fixes 3slow 3(24 3hr 3(can 3start 3with 3formalin
3and 3finish 3in 3alcohol 3to 3speed 3up)
glutaraldehyde 3fixation
- larger, 3slower 3penetration
- leaves 3free 3eldehyde 3(false
3PAS 3+) 3ox 3quickly 3(keep
3sealed)
for 3electron 3microscopy 3(harder, 3more 3links 3= 3ultrastructure
3preserved) 3fixes 3<2 3hours
Mechanism 3of 3fixation 3CORRECT 3ANSWER.1) 3formalin 3bind 3functional 3group
3and 3add 3CH2OH 3(temporary, 3can 3be 3washed 3away) 3adding 3OH 3group 3=
3hemiacetal
2) 3methylene 3bridge 3formation 3= 3link 3functional 3groups 3via 3OH
3(24hr 3to 3form) 3not 3easily 3reverse
Effects 3of 3fixation 3CORRECT 3ANSWER.Less 3eosin/anionic 3staining
1) methylene 3bridges 3and 3hemiacetal 3involves 3amino 3groups 3(cationic) 3(less
3stained)
= 3eosin 3(anionic) 3staining 3reduced
2) aminos 3not 3near 3others 3= 3only 3hemiacetal 3no 3bridge
these 3oxidized 3to 3carboxylic 3acid 3residues 3(neg) 3increased 3neg 3decreased 3eosin
