Researchers investigate Tgfbr1, a receptor protein pivotal in embryonic development pathways. They inactivated the gene to observe its impact on spinal cord development. Conclusion: Tgfbr1 protein plays a key role in determining whether primordial structures develop into genitalia or limbs by influencing DNA folding. Deactivating Tgfbr1 led to changes in gene activity, causing extra limbs to form and preventing the development of true external genitalia in mice.