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Biol Bull 72: 311-318. (June 1937)
© 1937 Marine Biological Laboratory
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ON THE SIGNIFICANCE OF THE POLAR SPOT IN RIPE UNFERTILIZED AND IN FERTILIZED ASCIDIAN EGGS

A. DALCQ 1 and G. VANDEBROEK 2

1 Brussels
2 Ghent

Ripe Ascidiella eggs have been subjected to local vital staining, chiefly in the regions surrounding the animal pole. Fertilization is immediately followed by a shift of the cortical layer towards the equator; when the yellow crescent appears, the material returns to its original position. The continuous observation of the ripe and the fertilized egg shows, contra Cohen and Berrill, that the polar spot marks the place where polocytes will be extruded.

In addition, attention is called to cases where there are two or three maturation spindles in the same egg.






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Copyright © 1937 by the Marine Biological Laboratory.