Hop in to find out how this toad-tally amazing discovery helped women find out if they were pregnant thanks to our froggy friends!
Before the early 20th century, women had no way of knowing if they were pregnant or not before getting physical signs – pregnancy tests like those available today did not exist yet. But from the 1930s up to until the 1960s, a croaking animal became the center of attention in biomedical research, presenting a solution to this problem: the African Clawed frog.
It was Lancelot Hogben, a British zoologist, who, at the start, was studying this frog for its ability to camouflage itself from its prey by changing color. This is due to the frog’s pituitary gland, a part of the brain that causes the release of hormones and controls growth, metabolism, and reproduction, amongst other necessary body functions. With two of his students, he tested the importance of the frog’s pituitary gland by removing it, which prevented the frog from changing color, leaving it white. After injecting a pituitary extract from an ox to see if the frog would change colors again, Hogbens triggered without meaning to the frog’s ovulation.
Hogbens knew that the pituitary extract from the ox contained a similar hormone to one present in the urine of pregnant women, the chorionic gonadotropin hormone (hCG), and thought that if this hormone from an ox triggered the frog to lay eggs, then injecting urine from a possibly pregnant woman would do the same thing. Thus, if the frog laid eggs, it would signal that the woman was indeed pregnant.
This was a revolutionary discovery for medicine as this was a much more practical and ethical(ish) way of testing for pregnancy than on mice or rabbits, which was a previous technique that was very time-consuming and needed for the animals to be killed and dissected to confirm the presence of hCG. The African Clawed frog would respond to the presence of hCG in about nine hours and their large ovaries would permit them to be test subjects multiple times, as well as their advantageous life span of 15 to 30 years.
A huge amount of these frogs were shipped to hospitals around the globe, enabling reliable and quick pregnancy tests. By the 1970s, these frogs were the stars of the biomedical stage!
Alas, some malicious frogs did escape laboratories, where they competed against other amphibians in their natural habitat. This frog carried an infectious fungus deadly to other amphibians called Chytrid fungus disease (Batrachochytrium dendrobatidis), and led to the extinction of species or endangered many aquatic populations. The African Clawed frog was later classified as an invasive species and made illegal in some countries. Thankfully, since then, we have been able to develop pregnancy tests that do not require these leaping animals!
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References:
https://en.wikipedia.org/wiki/Frog_test#:~:text=Hogben test,-African clawed frog&text=The Hogben test%2C named after,test which uses male frogs.
Note: the drawing of the frog's brain with the pituitary gland is only a model – this isn't really what a frog's brain looks like :)
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