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Animations : Beroe

930 Ko

The ctenophore Beroe ovata. Ctenophore move using 8 rows of comb plates called ctene made of cilia

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Fertilization in the ctenophore Beroe ovata. The sperm can be seen entering the egg (time-lapse / DIC).

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Fertilization in the ctenophore Beroe ovata. The sperm can be seen entering the egg witch contracts locally (time-lapse / DIC).

1,1 Mo

The egg pronucleus “choses” amongst several sperm nuclei. In this sequence the female pronucleus migrates from the animal pole (site polar bodies extrusion) towards one sperm pronucleus then toward another one. After fusion of the pronuclei, mitosis takes place and first cleavage initiate at that site (Beroe ovata / time-lapse / epifluorescence).

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Meeting of sperm and egg pronuclei. The larger egg nucleus migrates under the surface (Beroe ovata / time-lapse / epifluorescence).

	1,4 Mo	Displacement of the egg pronucleus under the surface (Beroe ovata/Time lapse/epifluorescence)
	990 Ko	Meeting of sperm and egg pronuclei. The larger egg nucleus migrates under the surface (Beroe ovata / time-lapse / epifluorescence).
	1 Mo	Random motion of the egg pronucleus in an unfertilized egg (Beroe ovata / time-lapse / epifluorescence).
	1 Mo	Female pronucleus “chosing” a male pronucleus. The larger egg pronucleus migrates and hesitates between several smaller pronuclei (Beroe ovata / time-lapse / epifluorescence).
	800 Ko	Fusion of egg and sperm nuclei. The smaller sperm nuclei is on the right (Beroe ovata / time-lapse / DIC).
	370 Ko	First mitosis in the egg of the ctenophore Beroe ovata. Chromosomes are labelled with Hoechst 3342 dye which binds to DNA (time lapse / epifluorescence)
	580 Ko	First unipolar cleavage in the large (1mm in diameter) egg of the ctenophore Beroe ovata.
	1,1 Mo	Development of the ctenophore embryo. Smaller blastomeres form by unequal cleavage in the vegetal pole region after the 8 cell stage (Beroe ovata, Natural fluorescence).

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., and Cooley, L. (2001). Comparative aspects of animal oogenesis. Dev. Biol. 231, 291-320.