Regeneration in Planarians Lab
Introduction
Before we begin this lab, you need to do some research about planarians and their regenerative properties. Please
research and answer the following questions – do not forget to cite your sources! Your answers to these questions will
be used in writing your background information section of your lab report so be thorough and be able to connect all the
information.
About planarians:
1. Find a picture of a “real” planarian (not a drawn or cartoon picture) and paste it into your lab document.
2. What type of animal is a planarian?
3. In what environment(s) are planarians normally found in nature?
4. Describe how a planarian eats.
5. What is the purpose of the planarian’s photoreceptors found in the eyespots? Label the photoreceptors and
eyespots in your planarian from question 1.
6. How do planarians reproduce? (there are two different ways, explain both)
7. What are neoblasts and what is their purpose in planaria?
8. Identify two ways in which planarians are being used for research.
About regeneration:
9. What is regeneration?
10. How is regeneration useful for organisms?
11. Name 3 organisms (other than planaria) that can regenerate.
12. What is cell differentiation? How does this happen?
13. How is protein synthesis related to cell differentiation?
14. What are stem cells?
15. Why are stem cells important?
16. Explain the term “stem cell niche”
Watch the video:
 http://www.hhmi.org/biointeractive/planarian-regeneration-and-stem-cells
Purpose
 To test the planarian’s ability to regenerate.
 To determine where stem cells are located in the planaria, based on the length of time it takes for the
photoreceptors in the eye spots to reappear.
Materials
 planarian culture (Dugesia dorotocephala)
 razor blades
 dropping pipets
 petri dishes
 stereomicroscope/dissecting scope
 spring water
Hypothesis
If different parts of the planaria body have equal ability to regenerate, they should all regenerate the head in the same amount of time.
If not, the closer a cut is made to the location of the stem cells in the planarian, the _______________ the photoreceptors will grow
back.
Procedure
1. Number the bottoms of three of the petri dishes 1 through 3, fill halfway with spring water, and set aside. (Marking the bottoms
will prevent confusion by accidental swapping of lids.)
2. Using a plastic transfer pipette, transfer a planarian into the remaining unlabeled empty plastic petri
dish.
3. Soak up excess water with a paper towel. Limiting the amount of water can reduce the mobility of the
planarian and facilitate the next step. Be careful not to touch the planarian—they will stick to the paper
and could then die.
4. Place the petri dish with the planarian under the dissecting microscope WITHOUT turning the light on.
Focus.
5. Using a scalpel, make Cut #1 to the planarian as indicated on the diagram on the right. Planarians can
move rapidly. Cutting them in a precise location can be difficult.
6. Using a transfer pipette, gently transfer the head fragment into the petri dish #1.
7. Repeat steps 5-6 for Cut #2, placing the mid-section in petri dish #2 and tail section in petri dish #3.
8. Repeat steps 2 through 7 with the remaining worms until dishes have at least three or four tail fragments of each of the three
cutting positions.
9. On the data table, draw each piece of your planaria in the correct section under Day 0.
Conclusion
1.
After you cut your planarian, how did the mobility of the tail fragments differ from the mobility of the head
fragments? Do they move the same or differently? If they move differently, why do you think this is?
2.
Describe the regeneration of piece 1 over time. Did it result in a complete (with eyespots and tail)
planarian?
3.
Describe the regeneration of piece 2 over time. Did it result in a complete (with eyespots and tail)
planarian?
4.
Describe the regeneration of piece 3 over time. Did it result in a complete (with eyespots and tail)
planarian?
5.
Discuss how the color of the regenerating parts changed over time? Explain why this difference in coloring
may have occurred.
6.
When the heads were growing back, do you think the eyespots were functional? How would you test this?
7.
Using your data table, did all the fragments regenerate photoreceptors at the same rate? Which were
slower and which were faster? (give specific piece numbers and days)
8.
What does the rate of appearance of photoreceptors in the different fragments tell you about the
regeneration ability of different sections of the worm? Based on your data, where might the main stem cell
niche be for the planarian? Why did you choose this area?
9.
Was your hypothesis correct? Explain why it was or wasn’t using your data table.
10.
Write a final statement about this lab. Use the terms stem cells, differentiation, and mitosis in your
conclusion.