Sea urchin developement (Paracentrotus lividus) from fertilization throught blastula stage (15 hours) (1,5 Mo)

The development of the european sea urchin (paracentrotus lividus) is filmed from fertilization through the blastula stage (15 hours) and speeded times.
Sequence from the film "Fertilization, the story of sperm and egg"

Reorganisations (ooplasmic segregation) in ascidians after fertilization (137 K0)

Ascidian eggs are characterized by the polarized distribution of 2 domains along the animal vegetal axis: a cortical ER-rich domain(red) and a subcortical mitochondria-rich domain (green). At fertilization the 2 domains are concentrated towards the contraction/vegetal pole by an acto-myosin driven cortical contraction. After completion of meiosis the bulk of the domains translocate towards the future posterior pole of the embryo.This is mediated by the rotation of the microtubular aster with respect to the cortex.
For more information see Roegiers et al (1999) Development 126, 3101-3117.

Germ granule and 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 (2002) 129, 661-670. PDF
"CellVirus" (5Mo)

Noe and NicoSardet have visited our site and produced "CellVirus" as part of a video competition (Concours Paradis/Enfer) .
This is their vision of Hell. Quite appropriate these days.

Ascidians and Sea Urchin Embryos develop together (2Mo)

The smaller sea urchins and bigger ascidian embryos develop together from the 2 cell stage. In this sequence speeded up about 2000 times the sea urchin ciliated blastula hatch out of their envelopes 1O hours after fertilizationand two ascidian embryos become tadpoles in 12 hours
Sequence from the teaching film "Fertilization, the story of sperm and egg" "
Clip of the month
January 2004. Fertilization in the comb jelly Beroe ovata (512 ko).
The ctenophore Beroe ovata produces large (1 mm) glass-clear eggs in wich sperm entry can be observed with exceptional clarity from profile or face on. Sperm entry produces a local contraction of the egg cortex. Many sperm can successively enter in the egg and several may be successively probed be the female pronucleus.
Sequence from the teaching film "Fertilization, the story of sperm and egg"
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Clip of the month