The Bead Experiment

by
Duncan Parks
Scientist

The Experiment

Dr. Stan Sessions did an experiment to see if trematode parasites could cause leg deformities in amphibians. He used surgery to put plastic beads into African Clawed Frog tadpoles. He put the beads in the tissue that would develop into the legs. This was where he had seen the trematode CYSTS

in wild frogs. Dr. Sessions thought the beads would act like the trematode cysts when he put them in the same place.

The Results

After the tadpoles went through metamorphosis, the rear legs were studied with x-ray photos. One of these x-rays is shown below.

IMAGE COURTESY OF DR. STAN SESSIONS

This is a photo of the foot of one of the frogs that had a bead implanted in it when it was a tadpole. The short arrow points to the bead that was implanted. The long arrow points to a place where one toe has branched into two -- the frog had grown SIX toes!

What do you conclude from this experiment?

Evidence Information

KEYWORDS	trematodes, supernumary limbs, resin beads, Xenopus laevis
SUBMITTER	Duncan Parks