Publication Date:
2006-06-17
Description:
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 lobeforming 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.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Chen, Jun-Yuan -- Bottjer, David J -- Davidson, Eric H -- Dornbos, Stephen Q -- Gao, Xiang -- Yang, Yong-Hua -- Li, Chia-Wei -- Li, Gang -- Wang, Xiu-Qiang -- Xian, Ding-Chang -- Wu, Hung-Jen -- Hwu, Yeu-Kuang -- Tafforeau, Paul -- New York, N.Y. -- Science. 2006 Jun 16;312(5780):1644-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Nanjing Institute of Geology and Paleontology, Institute of Evo/Developmental Biology, and State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing 210093, China. chenjy@nju.edu.cn〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/16778054" target="_blank"〉PubMed〈/a〉
Keywords:
Animals
;
Annelida/embryology
;
Biological Evolution
;
Blastomeres/cytology
;
China
;
Embryo, Nonmammalian/*anatomy & histology/cytology
;
*Embryonic Development
;
*Fossils
;
Geologic Sediments
;
Invertebrates/*embryology
;
Mollusca/embryology
;
Phosphates
;
Platyhelminths/embryology
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
,
Chemistry and Pharmacology
,
Computer Science
,
Medicine
,
Natural Sciences in General
,
Physics
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