1. Phospatized Polar Lobe-Forming Embryos from the Precambrian of Southwest China.
- Author
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Jun-Yuan Chen, Bottjer, David J., Eric H.Davidson, Dornbos, Stephen q., Xiang Giao, Yong-Hua Yang, Chia-Wei Li, Gang Li, Xiu-Qiang Wang, Ding-Chang Xiang, Hung-Jen Wu, Yeu-Kuang Hwu, and Tafforeau, Paul
- Subjects
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PRECAMBRIAN stratigraphic geology , *TRILOBITES , *FOSSIL arthropods , *EMBRYOS , *CYTOPLASM , *PROTOPLASM - Abstract
In developing embryos of some extant spiralian animals, polar lobe formation is one of the symmetry-breaking mechanisms for segregation of maternal cytoplasmic substances to certain blastomeres and not others. Polar Lobe formation leads to unique early cleavage morphologies that include trilobed, J-shaped, and five-lobed structures. Fossil embryos similar to modern lobe-forming embryos are recognized from the Precambrian Doushantuo Formation phosphates, Weng'an, Guizhou Province, China. These embryos are abundant and form a developmental sequence comparable to different developing stages observed in lobe-forming embryos of extant spiralians. These data imply that lobe formation is an evolutionarily ancient process of embryonic specification. [ABSTRACT FROM AUTHOR]
- Published
- 2006
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