Phosphatized polar lobe-forming embryos from the Precambrian of southwest China.
Science
; 312(5780): 1644-6, 2006 Jun 16.
Article
en En
| MEDLINE
| ID: mdl-16778054
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 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.
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Bases de datos:
MEDLINE
Asunto principal:
Desarrollo Embrionario
/
Embrión no Mamífero
/
Fósiles
/
Invertebrados
Límite:
Animals
País/Región como asunto:
Asia
Idioma:
En
Revista:
Science
Año:
2006
Tipo del documento:
Article
País de afiliación:
China