1. Separation of a pronucleus by premature cytokinesis: a mechanism for immediate diploidization of tripronuclear oocytes? 
Bernd E. Rosenbusch, Ph.D., Michael Schneider, Ph.D. 
Fertility and Sterility 
Volume 92, Issue 1, Pages 394.e5-394.e8 (July 2009)
DOI: /j.fertnstert
Copyright © 2009 American Society for Reproductive Medicine Terms and Conditions

2. Figure 1
(A) The oocyte seemed to posses two polar body (PB)–like structures (arrows) at metaphase II. (B) The pronuclear stage underwent premature cytokinesis. The smaller part of the ooplasm carries the two PB-like structures and an additionally extruded globule (arrows). (C) Two pronuclei (PN) (arrows) are located in the larger part of the divided cytoplasm. (D) A different focus reveals a total of three PN (arrows), one of which lies in the smaller cytoplasmic fragment. Scale bar = 50 μm.
Fertility and Sterility  , 394.e5-394.e8DOI: ( /j.fertnstert )
Copyright © 2009 American Society for Reproductive Medicine Terms and Conditions

3. Figure 2
Three chromosome sets could be observed after fixation, one of which carried an acentric fragment (arrow). Tentatively established karyotypes were 23,X; 23,X,ace; and 23,Y, respectively.
Fertility and Sterility  , 394.e5-394.e8DOI: ( /j.fertnstert )
Copyright © 2009 American Society for Reproductive Medicine Terms and Conditions