MODIFICATION OF CELL-MIGRATION PATTERNS IN THE EARLY CHICK EMBRYO

Abstract

Chick embryos were explanted before any sign of cardiac development and were cultured in vitro during the entire period of heart formation in the presence of acetylcholine. Of 43 chicks treated, abnormal fusion of the paired cardiac primordia in the mid-line occurred in 39.5%. In the cardia bifida chicks, before fixation, both hearts were usually beating, in all cases, independently of each other. Generally the left heart appeared to have the faster, stronger pulsation. Preliminary experiments with calcium-binding agents such as citrate and versene indicate that acetylcholine may function by limiting calcium ion availability to the endodermal and mesodermal cells of the embryo and thus disturb the normal intercellular relationships sufficiently to prevent migration and fusion of the cardiac anlagen.