07 July 2026
How a tiny signal that helps shape mouse teeth could improve regenerative medicine
A new study published in Development, reveals that the spatial pattern of Sonic hedgehog (Shh) signalling is a crucial blueprint for mouse incisors to develop their unique shape. The work opens new possibilities for understanding many developmental disorders and improving regenerative medicine.
From symmetry to asymmetry
Both mouse molars and incisors start as small, symmetrical tooth buds. However, as they grow, incisors become asymmetrical, with one side growing more than the other.
The study found that this happens because cells on one side of the developing incisor divide faster than cells on the opposite side.
The key driver is a signalling molecule called Sonic hedgehog (Shh).
What does Sonic hedgehog (Shh) do?
Shh is a signalling protein that tells cells where and when to grow during embryonic development. In this study, it acts like a growth-directing signal that helps shape the developing mouse incisor.
At an early stage of incisor development, Shh is produced mainly on one side of the tooth bud. This uneven signal causes more cell growth in that area, helping the tooth develop its characteristic asymmetrical shape.
When researchers blocked Shh signalling, the tooth buds became more symmetrical. Similarly, making Shh expression symmetrical by adding extra Shh to the opposite side had the same effect. The findings show that where Shh is expressed is more important than how much is present. Its uneven distribution directs growth to specific regions, shaping the developing tooth.
A blueprint for shaping organs
By controlling where cell proliferation happens, Shh plays a key role in forming the distinctive shape of the mouse incisor. The researchers suggest that understanding these processes could improve understanding of craniofacial and dental birth defects and help scientists grow replacement teeth with the correct shape by tuning the signalling.
Lead author Professor Jeremy Green, Professor of Developmental Biology Centre for Craniofacial & Regenerative Biology also noted the wider possibilities for understanding developmental disorders and improving regenerative medicine.
“More broadly, the findings reveal how local signalling molecules can influence the shape of developing organs. This could support future tissue engineering by using molecular signals to guide tissue shape, a process known as "morphogenetic steering."
The work is a companion to another paper that was recently chosen as the Journal of Anatomy’s Best Paper of 2025 looking at the mechanics of early tooth development: https://doi.org/10.1111/joa.14187
In this story
Professor of Developmental Biology