Gross Spatial Changes in the Turkey Blastoderm Following Extended Pre-Incubation Storage. ∗ †

Summary

Through a window in the shell, two sets of observations and linear measurements were made on the blastoderms of turkey (Broad Breasted Bronze) eggs held for 14 days at 13°C: one before and the other at the end of the holding period. At both times, free hand sketches were made of the gross morphology of the germ disc and its diameter was measured. The eggs were then incubated for 40 hours at 37.5°C and the blastoderm and the area pellucida were measured. A parallel series of observations was made on eggs in which the outer limits of the germ disc were marked (“tattooed”) before storage. During the holding period marked changes in the gross morphology of the turkey germ disc usually could be observed. The diameter of the germ disc also changed (“fluxed”) in most cases. Subsequently, early blastoderm growth at 37.5°C was favored by these changes.