Creating a six-legged mouse for the first time

In Oerias, Portugal, a team of scientists led by biologist Moisés Mallo has created a unique 6-legged mouse embryo with an extra pair of hind legs instead of external genitalia. The researchers at the Gulbenkian Institute of Sciences were studying a receptor protein called Tgfbr1, which plays a crucial role in embryonic development.

The Tgfbr1 gene codes for a transforming growth factor beta type 1 receptor that is involved in cellular responses like cell growth and division. Mutations in this gene can increase the risk of skin cancer. To study its effects on spinal cord development, the researchers stopped the activity of the Tgfbr1 gene in mouse embryos during pregnancy.

What they discovered was fascinating – Tgfbr1 dictates whether structures develop into genitals or legs. Inactivating the protein led to mice with extra legs and no external genitalia. This means that other genes are affected when Tgfbr1 is not active, leading to unexpected development outcomes.

The team plans 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, and their analysis did not differentiate between male and female embryos since their external genitalia do not differ. Further research will focus on understanding the broader implications of Tgfbr1 in development and disease.

Overall, this study highlights how even small changes in gene activity can have significant impacts on development outcomes, opening up new avenues for research into genetic disorders and diseases.

By Samantha Johnson

As a content writer at, I craft engaging and informative articles that aim to captivate readers and provide them with valuable insights. With a background in journalism and a passion for storytelling, I thoroughly enjoy delving into diverse topics, conducting research, and producing compelling content that resonates with our audience. From breaking news pieces to in-depth features, I strive to deliver content that is both accurate and engaging, constantly seeking to bring fresh perspectives to our readers. Collaborating with a talented team of editors and journalists, I am committed to maintaining the high standards of journalism upheld by our publication.

Leave a Reply