Nucleoli in a pronuclei-stage mouse embryo are represented by major satellite DNA of interconnecting chromosomes.

OBJECTIVE

To investigate the arrangement of chromosomes within pronuclei-stage mouse zygotes.

DESIGN

In vitro study.

SETTING

Academic medical center.

PATIENT(S): None.

INTERVENTION(S): None.

MAIN OUTCOME MEASURE(S): Location of major alpha-satellite DNA, centromeres, and telomeres, and relative location of chromosomes.

RESULT(S): Chromosomes appeared to be oriented inward by centromeres and to be interconnected by major alpha-satellite DNA, which appeared to be the sole DNA component of the nucleoli. This chromosomal arrangement persisted throughout interphase. Chromosomal painting failed to identify chromosomal ordering within pronuclei.

CONCLUSION(S): Pronuclear nucleoli are represented by alpha-satellite sequences of interconnecting chromosomes that hold all chromosomes together during interphase. Chromosomes within the pronucleus are randomly positioned relative to each other.