Influence of human sperm origin, testicular or ejaculated, on embryo morphokinetic development

In this retrospective observational study (October 2014 – July 2016), the impact of sperm origin on embryo morphokinetics and on clinical outcomes after intracytoplasmic sperm injection was evaluated. The developmental kinetics of embryos obtained either with testicular sperm (40 cycles; testicular sperm group) or with thawed donor sperm (26 cycles; donor sperm group) was analysed up to day-3 of culture with a time-lapse incubation system. In the testicular sperm group, all patients were affected by nonobstructive azoospermia. The timing of second polar body extrusion (IIPB), and the time to reach the 4-cells (t4) and 9-cells (t9) stages, differed significantly between the two groups: the IIPB extrusion and t4 were anticipated, whereas t9 was retarded in the testicular sperm group. We hypothesise that a different sperm maturation grade may influence the timing of embryo development: an early paternal effect of testicular sperm could be manifested as an anticipation in the IIPB extrusion and in the time for reaching the 4-cells stage. Conversely, a later paternal effect could be visible as a retardation in the timing at which the embryo reaches the 9-cells stage. Interestingly, clinical outcomes did not differ between the two groups except the implantation rate which was significantly increased in the donor sperm group.