Impregnation / Embedding
1. What is the main purpose of impregnation in histology?
A) To dehydrate tissues for easier storage
B) To remove all cellular components from the tissue
C) To replace the clearing agent with a medium that provides a firm consistency
D) To stain tissues for microscopic examination
Answer: C) To replace the clearing agent with a medium that provides a firm consistency
2. Which of the following is NOT a type of tissue impregnation and embedding medium?
A) Paraffin wax
B) Celloidin
C) Gelatin
D) Acetone
Answer: D) Acetone
3. What is the most commonly used infiltrating and embedding medium in histology?
A) Celloidin
B) Gelatin
C) Paraffin wax
D) Plastic
Answer: C) Paraffin wax
4. Which of the following is an advantage of paraffin wax impregnation?
A) Allows rapid preparation of sections within 24 hours
B) Requires no dehydration step
C) Does not cause shrinkage of tissues
D) Does not require heating
Answer: A) Allows rapid preparation of sections within 24 hours
5. What is the recommended immersion time for tissues in paraffin wax to prevent shrinkage and hardening?
A) Not more than 2 hours
B) Not more than 4 hours
C) Not more than 6 hours
D) Not more than 8 hours
Answer: B) Not more than 4 hours
6. Which of the following is NOT a method of paraffin wax impregnation?
A) Manual processing
B) Automatic processing
C) Vacuum processing
D) Electrochemical processing
Answer: D) Electrochemical processing
7. What is the function of the vacuum embedding method?
A) To remove excess wax from tissue samples
B) To speed up infiltration by removing air bubbles and clearing agents
C) To increase the melting point of the wax
D) To store tissues at lower temperatures
Answer: B) To speed up infiltration by removing air bubbles and clearing agents
8. In manual processing, how many changes of paraffin wax are required for proper impregnation?
A) 2
B) 3
C) 4
D) 6
Answer: C) 4
9. Which automatic processing machine is commonly used in tissue impregnation?
A) Electron microscope
B) Cryostat
C) Autotechnicon
D) Microtome
Answer: C) Autotechnicon
10. What is the routine melting point of paraffin wax used in histology?
A) 40°C
B) 48°C
C) 56°C
D) 65°C
Answer: C) 56°C
11. Which substitute for paraffin wax is commonly used for embedding neurological tissues and hard tissues like bones and teeth?
A) Carbowax
B) Celloidin
C) Tissue Mat
D) Polyester resin
Answer: B) Celloidin
12. What is the primary disadvantage of celloidin embedding?
A) Requires high temperatures
B) Cannot be used for histochemical staining
C) Takes a long time for impregnation (several days to weeks)
D) Causes excessive tissue shrinkage
Answer: C) Takes a long time for impregnation (several days to weeks)
13. Why is gelatin impregnation rarely used?
A) It requires heating above 100°C
B) It causes tissue hardening
C) It is water-soluble and difficult to section
D) It removes lipids from tissues
Answer: C) It is water-soluble and difficult to section
14. Which embedding method is best for whole eye sections?
A) Wet celloidin method
B) Vacuum embedding
C) Gelatin embedding
D) Dry celloidin method
Answer: D) Dry celloidin method
15. What is the purpose of embedding in histology?
A) To stain tissues for microscopic analysis
B) To make tissues transparent for better imaging
C) To provide a support medium for sectioning
D) To increase the dehydration process
Answer: C) To provide a support medium for sectioning
16. What is the primary precaution to take when using vacuum embedding?
A) Avoid overheating to prevent tissue shrinkage
B) Reduce dehydration time
C) Increase the clearing agent concentration
D) Avoid air exposure after embedding
Answer: A) Avoid overheating to prevent tissue shrinkage
17. Which embedding mold is adjustable and allows different tissue sizes?
A) Plastic Ice Trays
B) Paper Boats
C) Leuckhart’s Embedding Mold
D) Tissue-Tek System
Answer: C) Leuckhart’s Embedding Mold
18. What is the primary advantage of the Tissue-Tek system?
A) Uses minimal paraffin wax
B) Provides rapid embedding with easy orientation
C) Requires no refrigeration
D) Embeds tissues without prior impregnation
Answer: B) Provides rapid embedding with easy orientation
19. Which substitute for paraffin wax is commonly used for embedding undecalcified bones?
A) Tissue Mat
B) Ester Wax
C) Methyl Methacrylate (MMA)
D) Carbowax
Answer: C) Methyl Methacrylate (MMA)
20. Which of the following describes the double-embedding method?
A) Uses a combination of celloidin and paraffin embedding
B) Uses paraffin wax with added resins
C) Involves embedding in two different wax temperatures
D) Embeds tissues using two different dehydration agents
Answer: A) Uses a combination of celloidin and paraffin embedding
2. What happens if tissue is inadequately infiltrated during impregnation?
A) It becomes too rigid to section
B) It retains the clearing agent and remains soft
C) It shrinks excessively
D) It loses all cellular components
Answer: B) It retains the clearing agent and remains soft
3. Which of the following is the best embedding medium for routine histological procedures?
A) Gelatin
B) Paraffin wax
C) Celloidin
D) Carbowax
Answer: B) Paraffin wax
4. Which clearing agent is easiest to remove during paraffin impregnation?
A) Cedarwood oil
B) Chloroform
C) Benzene
D) Xylene
Answer: C) Benzene
5. Which of the following is a disadvantage of paraffin wax embedding?
A) Requires long processing time
B) Cannot be used for enzyme histochemistry
C) Makes section cutting difficult
D) Causes excessive tissue swelling
Answer: B) Cannot be used for enzyme histochemistry
6. What is the recommended embedding method for fatty tissues?
A) Paraffin wax
B) Water-soluble wax
C) Celloidin
D) Gelatin
Answer: B) Water-soluble wax
7. What is the ideal melting point of paraffin wax used in histology when the lab temperature is 20-24°C?
A) 45-48°C
B) 50-52°C
C) 54-58°C
D) 60-65°C
Answer: C) 54-58°C
8. How many wax changes are required in manual processing for complete impregnation?
A) 1
B) 2
C) 3
D) 4
Answer: D) 4
9. What is the function of the vacuum embedding technique?
A) To remove excess paraffin from tissues
B) To increase the porosity of tissues
C) To speed up impregnation and remove air bubbles
D) To replace paraffin wax with gelatin
Answer: C) To speed up impregnation and remove air bubbles
10. Which embedding medium is recommended for processing whole eye sections?
A) Paraffin wax
B) Celloidin
C) Carbowax
D) Gelatin
Answer: B) Celloidin
11. What is the purpose of using a cold plate during embedding?
A) To prevent tissue shrinkage
B) To solidify the embedding medium rapidly
C) To remove excess wax from tissue molds
D) To rehydrate tissue samples
Answer: B) To solidify the embedding medium rapidly
12. Which processing method uses an automatic tissue processor?
A) Manual processing
B) Vacuum embedding
C) Autotechnicon processing
D) Gelatin embedding
Answer: C) Autotechnicon processing
13. Which of the following is an advantage of the Tissue-Tek system?
A) Faster embedding and easier tissue orientation
B) Requires no dehydration
C) Does not require an embedding mold
D) Uses minimal reagents for impregnation
Answer: A) Faster embedding and easier tissue orientation
14. Which embedding mold consists of two L-shaped strips of heavy brass?
A) Tissue-Tek system
B) Leuckhart’s embedding mold
C) Paper boats
D) Disposable embedding mold
Answer: B) Leuckhart’s embedding mold
15. Which embedding method is best for hard tissues like bones and teeth?
A) Paraffin embedding
B) Gelatin embedding
C) Celloidin embedding
D) Vacuum embedding
Answer: C) Celloidin embedding
16. What is the main disadvantage of using the wet celloidin method?
A) It does not provide good support for tissues
B) It requires long processing time
C) It cannot be used for neurological tissues
D) It requires high temperatures
Answer: B) It requires long processing time
17. What is the advantage of using paraplast instead of paraffin wax?
A) Allows for better serial sectioning and is more elastic
B) Does not require dehydration
C) Melts at a lower temperature
D) Does not require a clearing agent
Answer: A) Allows for better serial sectioning and is more elastic
18. What is the function of plastic resins in embedding?
A) Used for light microscopy, especially in hard tissues like bone
B) Eliminates the need for dehydration
C) Used only for frozen sections
D) Provides a temporary embedding solution
Answer: A) Used for light microscopy, especially in hard tissues like bone
19. Which substitute for paraffin wax is used for enzyme histochemistry?
A) Ester wax
B) Carbowax
C) Tissue mat
D) Bioloid
Answer: B) Carbowax
20. Why should paraffin wax not be overheated?
A) It produces toxic fumes
B) It makes tissues brittle
C) It causes tissue shrinkage
D) Both B and C
Answer: D) Both B and C
21. What is the best embedding method for delicate specimens and frozen tissue sections?
A) Paraffin wax embedding
B) Gelatin embedding
C) Plastic resin embedding
D) Ester wax embedding
Answer: B) Gelatin embedding
22. Why is the dry celloidin method preferred for whole eye sections?
A) It prevents tissue distortion and maintains transparency
B) It allows rapid tissue penetration
C) It does not require fixation
D) It hardens tissues for easier sectioning
Answer: A) It prevents tissue distortion and maintains transparency
23. What is the main disadvantage of plastic resin embedding?
A) It requires a long processing time
B) It does not support hard tissues
C) It cannot be used for electron microscopy
D) It is highly toxic and expensive
Answer: D) It is highly toxic and expensive
24. What is the primary purpose of embedding?
A) To make tissue softer for sectioning
B) To remove excess clearing agent
C) To provide support for sectioning
D) To increase tissue transparency
Answer: C) To provide support for sectioning
25. Which embedding medium is used in the double-embedding method?
A) Gelatin
B) Paraffin wax and celloidin
C) Plastic resin
D) Ester wax
Answer: B) Paraffin wax and celloidin