Dorso‐ventral axis perturbation in goldfish embryos caused by heat‐ and pressure‐shock treatments for chromosome set manipulation

Effects of the chromosome set manipulation on early embryonic development were examined in goldfish and crucian carp. Both pressure‐ and heat‐shock treatments of fertilized eggs induced developmental disorders such as thin blastodisc formation, delay of epiboly, and deficiency of dorso‐anterior structures. The longer the treatments were applied to the eggs, the more frequently severe dorsal deficiencies were induced in the embryos. No and reduced signals of goosecoid mRNA, a dorsal mesodermal marker, were observed in embryos treated with heat‐shock at 40°C for 1 min at 5 min postfertilization. These results suggested that such treatments should affect not only the retention of the second polar body, but also the suppression of dorso‐ventral differentiation.