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