Alligators continually make new teeth to replace the ones they lose. A single gator can make 2,000 to 3,000 teeth in a lifetime, and according to HealthDay news on Tuesday, scientists say they have figured out how the animals do it.
New research, published in the May 13 edition of Proceedings of the National Academy of Science, gets to the root of the regeneration process and may one day help scientists regrow human teeth.
Many reptiles regenerate their teeth indefinitely, but for some reason mammals lost that ability. Humans, for example, grow one set of baby teeth, later replaced by adult chompers. After that our teeth stop coming in (apart from a few rare exceptions) because the dental lamina—a stem cell–laden layer of tissue in the gums that stimulates tooth growth—goes into latency after adult teeth come in.
Using a variety of methods -- including studying cells under a microscope, 3-D imaging and experimentation inside and outside the body -- researchers at the University of Southern California and other institutions found a thin layer of slow-growing stem cells that seemed to be responsible for replacing the reptiles' lost chompers.
"With the data that we've generated, it should be possible in the future to wake up those cells so that older people who've lost their teeth would be able to generate a third set," says Randall Widelitz, an author of the new paper. "But that's further down the line."
Mice currently serve as the model for studying tooth replacement in mammals, because they continuously grow their front incisors. However, the mouse is not an ideal model organism, as mice grow only one full set of teeth, and extending an incisor is not the same as producing a whole new set of teeth from scratch.
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