Effect of temperature differentials upon reconstitution of embryonic primordia in Ambystoma.

Eggs of Ambystoma maculatum in early stages of development were separated into two groups and maintained at 5 and 14 °C, respectively. In one series of animals comprising both temperature groups, the right otic vesicle was extirpated at stage 27. In another series the right forelimb disc was extirpated at stage 30. Following operation, animals of both groups were kept at 18 °C. Frequency and extent of reconstitution were compared between the two temperature groups. The 5° group was superior to the 14° group in the number of ears and forelimbs reconstituted. The extent of ear reconstitution and the initial quality of forelimb reconstitution were also superior in the 5° group. Statistical analysis of the data indicates that the difference between the two temperature groups is highly significant in both series. It is concluded that a slower pre-operative rate of development, caused by hypothermia, enhances the regenerative capacity of both ear and forelimb fields in the salamander embryo.