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.