title: Positional specification of blast cells in the leech embryo involves a stepwise commitment.
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000166:cytology / Q000502:physiology*; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000502:physiology; D007865:Leeches / Q000196:embryology*