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Updated: Aug 10, 2026
Understanding Early Organogenesis Using a Simplified In Situ Hybridization Protocol in Xenopus
Published on: January 12, 2015
Growth factors as inducing agents in early Xenopus development
1Department of Zoology, University of Oxford, UK.
Abstract:
Factors from two growth factor families have been identified as having mesoderm inducing activity. These include activin and TGF beta 2 from the TGF beta superfamily, and all members of the fibroblast growth factor (FGF) family. When isolated ectoderm explants are treated with any of these factors, a proportion of their cells are caused to differentiate into mesodermal tissue types instead of epidermis. There are several differences in the biological activities which can be broadly summarized by saying that activin yields dorsal type inductions and FGF ventral type inductions. Both bFGF and an FGF receptor have been detected in Xenopus blastulae, but it has not been shown that bFGF is normally secreted from vegetal cells. Various TGF beta-like mRNAs have also been detected and it is expected that an activin-like molecule will prove to be responsible for induction of the dorsal mesoderm in vivo.
Insights
Activin and fibroblast growth factors (FGFs) induce mesoderm in ectoderm. Activin promotes dorsal mesoderm, while FGFs induce ventral mesoderm, suggesting distinct roles in embryonic development.
Area of Science:
- Developmental biology
- Embryology
- Molecular biology
Background:
- Growth factors are crucial for embryonic development.
- Mesoderm induction is a key early developmental event.
- Fibroblast growth factors (FGFs) and TGF-beta superfamily members are implicated in mesoderm formation.
Purpose of the Study:
- To investigate the mesoderm-inducing activities of activin and FGFs.
- To differentiate the specific roles of activin and FGFs in dorsal vs. ventral mesoderm induction.
- To explore the presence and potential role of FGFs in Xenopus blastulae.
Main Methods:
- Treatment of isolated ectoderm explants with growth factors (activin, FGFs).
- Observation and analysis of cell differentiation into mesodermal tissues.
- Detection of FGF and FGF receptor in Xenopus blastulae.
- Detection of TGF-beta-like mRNAs.
Main Results:
- Both activin and FGFs induce mesodermal differentiation in ectoderm.
- Activin promotes dorsal mesoderm induction, while FGFs induce ventral mesoderm.
- Basic FGF (bFGF) and an FGF receptor are present in Xenopus blastulae.
- TGF-beta-like mRNAs are detected, and an activin-like molecule is hypothesized for dorsal mesoderm induction.
Conclusions:
- Activin and FGFs are key regulators of mesoderm induction with distinct dorsal-ventral patterning roles.
- FGF signaling is present in early Xenopus development.
- Further research is needed to confirm the in vivo role of activin-like molecules in dorsal mesoderm induction.
