First published online September 9, 2004
Development 131, 1901e (2004)
© The Company of Biologists Limited
Spleens to the left
Early vertebrate embryos are bilaterally symmetrical but mature internal
organs show consistent left-right (LR) asymmetry. The establishment of LR
positional information has been well studied, but how the organ primordia
interpret this information during asymmetric morphogenesis is unclear.
Hecksher-Sørensen and colleagues identify a specialised columnar
epithelium the splanchnic mesodermal plate (SMP) as the
organiser for the leftward growth of the spleno-pancreatic region under the
control of the LR asymmetry pathway in mice (see p.
4665). They report
that the asplenic mutant dominant hemimelia (Dh) lacks the
SMP, an initially bilateral structure surrounding the gut endoderm. Another
asplenic mutant carrying a Bapx1-targeted disruption has a defective
SMP, indicating that Bapx1 regulates the SMP functions that are
required for spleno-pancreatic laterality. Given that the Bapx1 and
Dh mutants have normal hearts, lungs and livers, the researchers
suggest that LR positional information is interpreted differently by each
organ primordia.

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Related articles in Development:
- The splanchnic mesodermal plate directs spleen and pancreatic laterality, and is regulated by Bapx1/Nkx3.2
- Jacob Hecksher-Sørensen, Robert P. Watson, Laura A. Lettice, Palle Serup, Lorraine Eley, Carlo De Angelis, Ulf Ahlgren, and Robert E. Hill
Development 2004 131: 4665-4675.
[Abstract]
[Full Text]