Axes formation is a fundamental process of early embryonic development. In addition to the anteroposterior and dorsoventral axes, the determination of the left-right axis is crucial for the proper morphogenesis of internal organs and is evolutionarily conserved in vertebrates. Genes known to be required for the normal establishment and/or maintenance of left-right asymmetry in vertebrates include, for example, components of the TGF-β family of intercellular signalling molecules and genes required for node and midline function. We report that Notch signalling, which previously had not been implicated in this morphogenetic process, is required for normal left-right determination in mice. We show, that the loss-of-function of the delta 1(Dll1) gene causes a situs ambiguous phenotype, including randomisation of the direction of heart looping and embryonic turning. The most probable cause for this left-right defect in Dll1 mutant embryos is a failure in the development of proper midline structures. These originate from the node, which is disrupted and deformed in Dll1 mutant embryos. Based on expression analysis in wild-type and mutant embryos, we suggest a model, in which Notch signalling is required for the proper differentiation of node cells and node morphology.
Node and midline defects are associated with left-right development inDelta1 mutant embryos Available to Purchase
These authors contributed equally to this work
These authors contributed equally to this work
These authors contributed equally to this work
These authors contributed equally to this work
Gerhard K. H. Przemeck, Ulrich Heinzmann, Johannes Beckers, Martin Hrabé de Angelis; Node and midline defects are associated with left-right development inDelta1 mutant embryos. Development 1 January 2003; 130 (1): 3–13. doi: https://doi.org/10.1242/dev.00176
Download citation file:
Sign in
Client Account
Sign in via your institution
Sign in via ShibbolethAdvertisement
Interviews with Biologists @ 100 conference speakers

Explore our interviews with keynote speakers from the Biologists @ 100 conference, hosted to celebrate our publisher’s 100th anniversary, where we discuss climate change and biodiversity with Hans-Otto Pörtner and Jane Francis, health and disease with Charles Swanton and Sadaf Farooqi, and emerging technologies with Manu Prakash and Jennifer Lippincott-Schwartz.
Call for papers – Lifelong Development: the Maintenance, Regeneration and Plasticity of Tissues

Development invites you to submit your latest research to our upcoming special issue – Lifelong Development: the Maintenance, Regeneration and Plasticity of Tissues. This issue will be coordinated by Guest Editors Meritxell Huch (Max Planck Institute of Molecular Cell Biology and Genetics, Germany) and Mansi Srivastava (Harvard University and Museum of Comparative Zoology, USA), working alongside our team of academic Editors. Submit your articles by 30 May 2025.
A case for broadening our view of mechanism in developmental biology

In this Perspective, B. Duygu Özpolat and colleagues survey researchers on their views on what it takes to infer mechanism in developmental biology. They examine what factors shape our idea of what we mean by ‘mechanism’ and suggest a path forward that embraces a broad outlook on the diversity of studies that advance knowledge in our field.
In preprints
Did you know that Development publishes perspectives on recent preprints? These articles help our readers navigate the ever-growing preprint literature. Together with our preprint highlights service, preLights, these perspectives help our readers navigate the ever-growing preprint literature. We welcome proposals for ‘In preprints’ articles, so please do get in touch if you’d like to contribute.
the Node: Have your say

Our community site, the Node, is conducting a user survey about the content and the design of the site. Help us shape the Node's future and thank you for being a part of the Node over the last 15 years.