Sperm nuclei entering parthenogenetically activated mouse oocytes before the first mitosis transform into pronuclei. An ultrastructural study.
BACKGROUND
This report is an extension of previous observations (Maleszewski 1992. Mol. Reprod. Dev., 33:215-221) on the behavior of mouse sperm nuclei incorporated into parthenogenetically activated mouse oocytes prior to the first cleavage division and undergoing transformation during mitosis.


METHODS
Artificially activated mouse oocytes were inseminated in vitro and an ultrastructural analysis was performed of sperm-derived nuclei present in two parthenogenetic two-cell embryos.


RESULTS
Both chromatin and nuclear envelope of sperm derived-nuclei are structurally identical with those of oocyte-derived nuclei and of the nuclei of blastomeres of normal two-cell embryos.


CONCLUSIONS
Cytoplasm of the parthenogenote during the first mitotic division has the ability to transform sperm nucleus into a male pronucleus just like the cytoplasm of a metaphase II oocyte.
Maleszewski
M
M
Department of Embryology, University of Warsaw, Poland.
D000818:Animals; D002454:Cell Differentiation; D002467:Cell Nucleus / Q000648:ultrastructure*; D005260:Female; D008297:Male; D051379:Mice; D008854:Microscopy, Electron; D008938:Mitosis / Q000502:physiology*; D009865:Oocytes / Q000648:ultrastructure; D010312:Parthenogenesis; D013084:Sperm-Ovum Interactions / Q000502:physiology*