Summary
We exposed st.10 chicks to retinoic acid (RA), both globally, and locally to individual rhombomeres, to look at its role in specification of various aspects of hindbrain derived morphology. Previous studies have looked at RA exposure at earlier stages, during axial specification. Stage 10 is the time of morphological segmentation of the hindbrain and is just prior to neural crest migration. Rhombomere 4 localised RA injections result in specific alterations of pathways some crest cells that normally migrate to sites of differentiation of neurogenic derivatives. The r4 crest cells that give rise to mesenchymal derivatives are unaffected. In addition, r4 gene expression is also partially altered by RA; within 6 hours of r4 exposure to RA, ectopic expression of Krox-20 is seen in r4 and Hoxb-1 expression is lost while Hoxa-2 expression continues normally. When we examined these RA-treated animals later in development, they showed an anterior displacement of the facial ganglion in addition to a mis-direction of the extensions of its distal axons and a dramatic decrease in the number of contralateral vestibuloacoustic neurons normally seen in r4. Only this r4-specific neuronal type is affected in r4; the motor neuron projections seem normal in experimental animals. The specificity of this result, combined with the loss of Hoxb-1 expression in r4 and the work by Krumlauf and co-workers showing gain of contralateral neurons co-localised with ectopic Hoxb-1 expression, indicates a role for Hoxb-1 and RA in the specification of this cell type in normal development. These results suggest that RA, at st.10, is able to affect some aspects of segment identity while leaving others unchanged.
Article navigation
Related articles
Cited by...
More in this TOC section
Similar articles
Other journals from The Company of Biologists
An interview with Swathi Arur
Swathi Arur joined the team at Development as an Academic Editor in 2020. Her lab uses multidisciplinary approaches to understand female germline development and fertility. We met with her over Zoom to hear more about her life, her career and her love for C. elegans.
Jim Wells and Hanna Mikkola join our team of Editors
We are pleased to welcome James (Jim) Wells and Hanna Mikkola to our team of Editors. Jim joins us a new Academic Editor, taking over from Gordan Keller, and Hanna joins our team of Associate Editors. Find out more about their research interests and areas of expertise.
New funding scheme supports sustainable events
As part of our Sustainable Conferencing Initiative, we are pleased to announce funding for organisers that seek to reduce the environmental footprint of their event. The next deadline to apply for a Scientific Meeting grant is 26 March 2021.
Read & Publish participation continues to grow
“I’d heard of Read & Publish deals and knew that many universities, including mine, had signed up to them but I had not previously understood the benefits that these deals bring to authors who work at those universities.”
Professor Sally Lowell (University of Edinburgh) shares her experience of publishing Open Access as part of our growing Read & Publish initiative. We now have over 150 institutions in 15 countries and four library consortia taking part – find out more and view our full list of participating institutions.
Upcoming special issues
Imaging Development, Stem Cells and Regeneration
Submission deadline: 30 March 2021
Publication: mid-2021
The Immune System in Development and Regeneration
Guest editors: Florent Ginhoux and Paul Martin
Submission deadline: 1 September 2021
Publication: Spring 2022
Both special issues welcome Review articles as well as Research articles, and will be widely promoted online and at key global conferences.
Development presents...
Our successful webinar series continues into 2021, with early-career researchers presenting their papers and a chance to virtually network with the developmental biology community afterwards. Here, Michèle Romanos talks about her new preprint, which mixes experimentation in quail embryos and computational modelling to understand how heterogeneity in a tissue influences cell rate.
Save your spot at our next session:
10 March
Time: 9:00 (GMT)
Chaired by: Thomas Lecuit
Join our mailing list to receive news and updates on the series.