HOW FROGS ONCE WAS USED AS PREGNANCY TESTS

In this meaningful TED-Ed lesson written by Dr. Carly Ann York and animated by Yajun Shi, narrator Alexandra Panzer explains how  female African clawed frogs (Xenopus laevis) have the ability to constantly produce eggs. It explains how it was once used to detect pregnancy. In humans. Also, unlike the rabbits  used previously, the frogs were not subsequently dissected. 

"They responded to hCG within about nine hours, without the need for dissection. And because their large ovaries constantly produce eggs, they participated in numerous trials over their 15- to 30-year lifespan." Even better, these frogs were common in their natural habitat.'' This made it easier to find, catch, and export the frogs. This has led to  these frogs being present in hospitals around the world. Unfortunately, this had an unexpected but not surprising side effect. ” 

“Many of these amphibians have escaped from laboratory enclosures, and in many places their ferocious appetites have allowed them to outcompete native amphibians. In the 20th century, this fungal infection decimated amphibian populations around the world, causing a number of infections. We made that frog species extinct.” 

This practice continued into his 1970s. Since then, doctors have had access to chemical tests that can detect the presence of hCG, which indicates pregnancy. The use of Xenopus was then made illegal, and its presence is now considered invasive. 

“…Xenopus is currently considered an invasive species and is illegal in many areas. Ultimately, like other pregnancy tests,  these frogs were used in scientific research with both positive and negative results. ”