Planarians are simple multicellular animals called flatworms. More than 100 years ago, scientists figured out that some planarians can regenerate parts of their bodies. How is this possible? Planarians have adult stem cells called neoblasts throughout their bodies. When a planarian is cut, its neoblasts multiply to make more stem cells. These stem cells then differentiate into the cells needed to replace the missing body parts. These regeneration abilities are far beyond those of the human body. However, understanding how planarians are able to regenerate lost tissues and body parts may provide clues for how to improve wound healing in humans.
How a planarian regenerates depends on where the planarian was cut. Some planarians may even regenerate two heads in place of one. A piece cut from a planarian can also form a new planarian. This new planarian regrows a head and a tail region in the appropriate places…most of the time. Cut planarians that have certain genes shut down by RNAi can incorrectly form two heads instead of one head and one tail.
The downloadable Educator Materials PDF includes background information and implementation suggestions for using the images as an anchoring phenomenon. The Student Handout includes the images and background information.
Image Credits: Courtesy of Alice Accorsi, PhD, and Alejandro Sánchez Alvarado, PhD, Stowers Institute for Medical Research
Figures 1 and 2 from:
Hands-On Classroom Activities for Exploring Regeneration and Stem Cell Biology with Planarians. Alice Accorsi, Monique M. Williams, Eric J. Ross, Sofia M. C. Robb, Sarah A. Elliott, Kimberly C. Tu, Alejandro Sánchez Alvarado. The American Biology Teacher, Vol. 79 No. 3, March 2017; (pp. 208–223) DOI: 10.1525/abt.2017.79.3.208. http://abt.ucpress.edu/content/79/3/208
Date Created 11/19/2018
Date Modified 11/19/2018
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