Abstract
During vertebrate embryonic development, the organs of the chest and abdomen, heart, lung and gastrointestinal tract, acquire characteristic asymmetric positions with respect to the left-right body axis. In the beginning of the 20th century Hans Spemann and his co-workers described manipulations of amphibian embryos which resulted in inversion of organ laterality in a predictable manner. Hedwig Wilhelmi concluded from these experiments that determinants on the left side of the embryo specify laterality, and Meyer postulated that a mediator should transfer this positional information to the forming heart. In this review we discuss the classical experiments in the light of recent advances in the molecular understanding of left-right development, with a focus on the mediator role of the homeobox gene Pitx2.
Publication types
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Research Support, Non-U.S. Gov't
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Review
MeSH terms
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Amphibians / embryology
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Animals
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Body Patterning / physiology*
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Developmental Biology / methods*
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Developmental Biology / trends
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Embryo, Nonmammalian
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Functional Laterality
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Gene Expression Regulation, Developmental
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Homeobox Protein PITX2
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Homeodomain Proteins / genetics
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Homeodomain Proteins / metabolism
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Morphogenesis
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Nodal Protein
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Nuclear Proteins*
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Paired Box Transcription Factors
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Signal Transduction*
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Transcription Factors / genetics
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Transcription Factors / metabolism
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Transforming Growth Factor beta / genetics
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Transforming Growth Factor beta / metabolism
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Vertebrates / embryology*
Substances
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Homeodomain Proteins
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Nodal Protein
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Nuclear Proteins
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Paired Box Transcription Factors
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Transcription Factors
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Transforming Growth Factor beta
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homeobox protein PITX1
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homeobox protein PITX3