Chromatin and DNA of yolk granules beneath "blastoderm region" of unfertilized chicken egg.

Electron microscopic study shows that the chromatin structure of yolk granules beneath the "blastoderm region" of the unfertilized chicken egg is identical to that of yolk granules beneath the blastoderm of the fertilized and unincubated chicken egg, and both chromatin structures are very similar to those of blastoderm nuclei. Furthermore the molecular shapes of DNA of both yolk granules are also very similar to those of the blastoderm nuclei, being all linear. Based on these observations, we have come to the conclusion that chromatin and DNA widely exist in the yolk when yolk granules have reached their development-specified competence. The results indicate further that the yolk granules are capable of synthesizing DNA, and provide the condition for the interaction of DNA with histones to form chromatin through self-organization.