Role of the acetylcholine-cholinesterase system in the spontaneous rhythmical activity of the amnion of the chick embryo

Summary A biphasic change was seen to occur in the acetylcholine content of the amnion muscular tissue during the development of the chick embryo (5th–13th incubation days). From the 5th to the 8th day the amount of acetylcholine exhibited a considerable rise: from the 8th to 13th day a marked reduction of the acetylcholine content was revealed in the tissue. Within the same period the cholinesterase activity is also seen to change, showing a marked reduction from the 5th to the 8th day, a slight rise on the 11th day, this being followed again by a drop.The change of the acetylcholine content and of the cholinesterase activity is accompanied with reduction of the SH-group concentration in the tissue; a sharp one from the 5th to the 8th day then becoming smoother from the 8th to 13th day. It is pointed out that the changes in the acetylcholine—cholinesterase system are linked with those in the frequency of spontaneous rhythmical contractions of the amnion.(Presented by Active Member AMN SSSR S. E. Severin) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 55, No. 1, pp. 17–21, January 1963