Nuclear fine structure and transcription in early goat embryos

Abstract

Early preimplantation goat embryos were investigated for the onset of major gene transcription by fine-structure morphology and autoradiographic detection of (5- 3H)uridine incorporation. Complex nuclear bodies were already seen in early pronuclei but only in the 16-cell embryos did these methodologies offer clear-cut evidence of the already fully-developed nucleolar structure as well as of nucleoplasm labeling. Nucleoplasm labeling, which is supposed to detect the onset of major transcription, was absent in the pronuclear and the 2- to 4-cell embryos. The first (5- 3H)uridine incorporation was detected in the 8-cell stage nuclei nucleoplasm, followed by nucleolar labeling. Based on this evidence, we found that in comparison with other ruminants, there is no striking difference in the timing of the shift in control from the maternal to the embryonic genome in the development of the early goat embryo.