[Acetylcholinesterase distribution in the blastoderm of chick embryos].

The distribution of acetylcholine esterase (AChE; EC 3.1.1.7) was studied cytochemically in the blastoderm of chick embryos (stages 2-5 by Hamburger and Hamilton). The onset of primitive streak formation was accompanied by a sharp increase in the AChE activity in the anterior part of hypoblast. Changes in the AChE distribution during the early embryogenesis correlated fairly well with the movement of the primary hypoblast cells.