Creating a six-legged mouse for the first time

In Portugal, scientists have made a groundbreaking discovery by creating a 6-legged mouse embryo with an extra pair of hind legs instead of external genitalia. Mois├ęs Mallo, a biologist at the Gulbenkian Institute of Sciences in Oerias, Portugal, and his colleagues are studying the role of a receptor protein called Tgfbr1 in embryonic development. They discovered that the Tgfbr1 gene codes for a protein called transforming growth factor beta type 1 receptor, which is involved in cellular responses like cell growth and division. The researchers stopped the activity of the Tgfbr1 gene in mouse embryos during pregnancy to study its effects on spinal cord development.

The team found that Tgfbr1 dictates whether structures develop into genitals or legs. This means that inactivating the protein can alter the activity of other genes, resulting in mice with extra legs and no external genitalia. The researchers plan to investigate how Tgfbr1 and related genes affect other systems, such as cancer metastasis, and whether similar processes occur in reptiles with double penises.

The embryos used in the study were collected from mice aged 3-6 months. The research team dissected the embryos and analyzed them further without distinguishing between male and female embryos since their external genitalia do not differ. Further research will focus on understanding the broader implications of the Tgfbr1 gene in development and disease.

In conclusion, this fascinating discovery sheds light on how genetic mutations can impact an organism’s development and lead to unexpected outcomes such as extra legs instead of external genitalia. This research opens up new avenues for understanding how genes interact with each other during development and how these interactions can influence an organism’s overall health and well-being.

By Riley Johnson

As a content writer at, I dive into the depths of information to craft compelling stories that captivate and inform readers. With a keen eye for detail and a passion for storytelling, I strive to create engaging content that resonates with our audience. Whether it's breaking news, in-depth features, or thought-provoking opinion pieces, I am dedicated to delivering high-quality, informative content that keeps readers coming back for more. My goal is to bring a fresh perspective to every article I write and to make a meaningful impact through the power of words.

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