The large Germ Granule of Chaetognaths
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500 Ko
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Formation of the Germ Granule in the Chaetognath Saggita bipunctata: The 20 microns large Germ Granule forms at the time of first mitosis via the swirling aggregation of smaller vegetal particles in about 10 minutes . |
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1.5 Mo
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The Germ Granule in the Chaetognath Saggita bipunctata forms in the vegetal cortex :The Germ granule forms (top of the egg) between the time male and female pronuclei meet and first mitosis (about 10 minutes). The Germ Granule is inherited by one of the first 2 blastomeres. The egg is 300 microns in diameter. |
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1.5 Mo
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Development of the Chaetognath Saggita bipunctata from stage 2 to juvenile: Waves of mitosis traverse the embryo which gastrulates and elongates its tail within the chorion. |
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2.5 Mo
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Germ
granule & germ cells in Chaetognaths (2.5Mo)
Chaetognaths (arrow worms) have 4 gonads filled with eggs and sperm can
be observed in vivo throughout their 1-2 month life cycle. A large (20 microns)
germ granule forms by a spiralling aggregation of particles in the vegetal
pole at the time of first mitosis and partitions into a single blastomere
until the 64 cell stage when the 4 founder primary germ cells give rise
to the 4 gonads. See Carré, Djediat , Sardet, Development, 129, February 2002 . |