A preliminary concept, deduced from cytogenetic analyses, for explaining different types of multipronuclear oocytes obtained after intracytoplasmic sperm injection.

摘要

Oocytes with three or more pronuclei and one or two polar bodies arising after intracytoplasmic sperm injection were analyzed cytogenetically, and the data were used to develop a general model explaining the possible origin of the abnormal pronuclear stages. The mechanisms, either separately or in variable combinations, that induce the appearance of additional pronuclei are: 1) nonextrusion of the second polar body; 2) incomplete chromatid segregation into the extruded second polar body; and 3) dispersal of the oocyte chromatids in the presence of the second polar body formation.