The notion that the intrinsic orientation of the early blastomeres is
different than what is seen with the egg shell as a spatial constraint
and as a reference coordinate system originates from a work of Einhard
Schierenberg: Reversal of Cellular Polarity and Early Cell-Cell
Interactions in the Embryo of Caenorhabditis elegans. Dev. Biol. 122,
452-463 (1987).
Richard Feichtinger
feichtin at alf.biochem.mpg.de