Fertilization abnormalities and pronucleus size asynchrony after intracytoplasmic sperm injection are related to oocyte postmaturity  Pravin Goud, M.D., Anuradha Goud, Ph.D., Patrick Van Oostveldt, Ph.D., Josiane Van der Elst, Ph.D., Marc Dhont, M.D., Ph.D.  Fertility and Sterility  Volume 72, Issue 2, Pages 245-252 (August 1999) DOI: 10.1016/S0015-0282(99)00231-9

Fig. 1 Zygotes obtained after intracytoplasmic sperm injection of in vitro matured oocytes. (A), A zygote with two pronuclei with similar diameters. (B to D), zygotes with significant pronucleus size asynchrony. Original magnification, ×320. Bar, 50 μm. Fertil Steril ©1999 Fertility and Sterility 1999 72, 245-252DOI: (10.1016/S0015-0282(99)00231-9)

Fig. 2 A box and whiskers plot displaying the differences in the diameters of the two pronuclei in the 2PN zygotes of all the groups. The horizontal lines within the boxes represent medians and the upper and lower borders of the boxes represent 75th and 25th percentiles, respectively. The horizontal lines above and below the boxes represent the largest and smallest values, respectively, that were not outliers. □ represent outliers. †P<.001. Fertil Steril ©1999 Fertility and Sterility 1999 72, 245-252DOI: (10.1016/S0015-0282(99)00231-9)

Fig. 3 A box and whiskers plot displaying the diameters of the smaller pronuclei of the 2PN zygotes in all the groups. □ represent outliers and ∗ represent extremes. For more details, refer to the legend for Fig. 2. †P<.04. Fertil Steril ©1999 Fertility and Sterility 1999 72, 245-252DOI: (10.1016/S0015-0282(99)00231-9)

Fig. 4 Injection of spermatozoa prelabeled with Mitotracker FM dye into in vitro matured oocytes that were intentionally aged for at least 6–8 hours after maturation. The images are optical sections obtained with a confocal laser scanning microscope. (A and B), Optical sections of the same zygote showing the female and male pronuclei, respectively. The fluorescent sperm midpiece remnant is indicated by a small arrow in (B). (C), A zygote with a significant size asynchrony between its pronuclei. The smaller male pronucleus can be identified from its proximity to the fluorescent sperm midpiece remnant (small arrowhead). The apparently smaller oocyte diameter in (C) is due to the peripheral location of the pronuclei. (D), A magnified image of an intact spermatozoon within an oocyte displaying only the female pronuclei. Bright labeling of the sperm midpiece and tail are clearly evident (small arrowheads). Original magnification, ×600. Bars: (A to C), 50 μm. (D), 5 μm. Fertil Steril ©1999 Fertility and Sterility 1999 72, 245-252DOI: (10.1016/S0015-0282(99)00231-9)