Left-right asymmetric morphogenesis in the Xenopus digestive system.
The morphogenetic mechanisms by which developing organs become left-right asymmetric entities are unknown. To investigate this issue, we compared the roles of the left and right sides of the Xenopus embryo during the development of anatomic asymmetries in the digestive system. Although both sides contribute equivalently to each of the individual digestive organs, during the initial looping of the primitive gut tube, the left side assumes concave topologies where the right side becomes convex. Of interest, the concave surfaces of the gut tube correlate with expression of the LR gene, Pitx2, and ectopic Pitx2 mRNA induces ectopic concavities in a localized manner. A morphometric comparison of the prospective concave and convex surfaces of the gut tube reveals striking disparities in their rate of elongation but no significant differences in cell proliferation. These results provide insight into the nature of symmetry-breaking morphogenetic events during left-right asymmetric organ development.
Muller
Jennifer K
JK
Department of Biology, Collegium of Natural Sciences, Eckerd College, St. Petersburg, Florida 33711, USA.
Prather
Deva R
DR
Nascone-Yoder
Nanette M
NM
D000818:Animals; D019521:Body Patterning; D002455:Cell Division; D019070:Cell Lineage; D041981:Gastrointestinal Tract / Q000033:anatomy & histology* / Q000196:embryology*; D005775:Gastrula / Q000378:metabolism; D018398:Homeodomain Proteins / Q000096:biosynthesis; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008648:Mesoderm / Q000378:metabolism; D008856:Microscopy, Fluorescence; D009024:Morphogenesis; D012333:RNA, Messenger / Q000378:metabolism; D013997:Time Factors; D014018:Tissue Distribution; D014157:Transcription Factors / Q000096:biosynthesis; D014982:Xenopus laevis / Q000196:embryology*; D000097577:Homeobox Protein PITX2
D018398:Homeodomain Proteins; D012333:RNA, Messenger; D014157:Transcription Factors; D000097577:Homeobox Protein PITX2