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Updated: Jul 31, 2026
15:42
Double Whole Mount in situ Hybridization of Early Chick Embryos
Published on: October 27, 2008
Cell interactions underlying notochord induction and formation in the chick embryo
K H Healy1, G C Schoenwolf, D K Darnell
1Department of Biology, Lake Forest College, 555 N. Sheridan Road, Lake Forest, IL 60045, USA.
Summary
The chick embryo
Area of Science:
- Developmental biology
- Embryology
- Cell signaling
Background:
- Notochord development in chick embryos is traditionally linked to Hensen's node.
- Previous studies suggested roles for extra-nodal regions (inducer, responder, postnodal region) in notochord formation.
- The precise contribution and interaction of these regions in normal notochord development remained unclear.
Purpose of the Study:
- To investigate the timing and cellular interactions governing notochord induction and formation in chick embryos.
- To clarify the roles of Hensen's node, inducer, responder, and postnodal region in notochord development.
- To elucidate the regulatory mechanisms controlling notochord specification.
Main Methods:
- Transection experiments on chick blastoderm isolates.
- Grafting experiments to assess tissue interactions.
- Analysis of notochord formation at specific developmental stages (3a/b and 4).
Main Results:
- The rostral primitive streak, including Hensen's node, is not essential for notochord formation in early isolates.
- The inducer and postnodal region are not required for initial rostral notochordal cell formation, but the inducer promotes elongation.
- The responder is not strictly required if inducer and postnodal regions are present, but its absence reduces frequency; the node specifies notochord at stage 4.
Conclusions:
- Notochord formation involves complex interactions beyond Hensen's node, with early roles for the inducer and postnodal region.
- A negative feedback loop between Hensen's node specification and inducer activity likely regulates notochord development.
- A model is proposed for the regulation of organizer activity in the node during chick embryogenesis.
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