Morphokinetics as a predictor of self-correction to diploidy in tripronucleated intracytoplasmic sperm injection–derived human embryos  Noelia Grau, Ph.D., Laura Escrich, Ph.D., Yolanda Galiana, Ph.D., Marcos Meseguer, Ph.D., Sandra García-Herrero, Ph.D., José Remohí, M.D., María-José Escribá, Ph.D.  Fertility and Sterility  Volume 104, Issue 3, Pages 728-735 (September 2015) DOI: 10.1016/j.fertnstert.2015.05.024 Copyright © 2015 American Society for Reproductive Medicine Terms and Conditions

Figure 1 Graphic representation of embryo developmental events (model A) to determine direct and indirect morphokinetic variables. The time reference (t0) is the intracytoplasmic sperm injection (ICSI) event. The direct morphokinetic variables were the time points of embryo cleavage to the 2-, 3-, 4-, 5-, 6-, 7-, and 8-cell stages (t2, t3, t4, t5, t6, t7, and t8). The indirect morphokinetic variables were: duration of the second cell cycle of the first blastomere to cleave from the 2- to the 3-cell stage (cc2a = t3 − t2); duration of the second cell cycle of the second blastomere to cleave from the 2- to the 4-cell stage (cc2b = t4 − t2); and duration of the third cell cycle of the first (cc3a = t5 − t3), second (cc3b = t6 − t4), third (cc3c = t7 − t4), and fourth (cc3d = t8 − t4) blastomeres to cleave to the 5-, 6-, 7-, and 8-cell stages, respectively. Fertility and Sterility 2015 104, 728-735DOI: (10.1016/j.fertnstert.2015.05.024) Copyright © 2015 American Society for Reproductive Medicine Terms and Conditions

Figure 2 Graphic representation of the six feasible embryo models, according to blastomere cleavage patterns. To determine the blastomere cleavage pattern of tripronucleated intracytoplasmic sperm injection–derived (diploid and triploid) and bipronucleated embryos, early cleavages were tracked according to the 3-day recordings of each embryo. Following the first cleavage, two blastomeres were obtained. Subsequent cleavage brought the embryo to the 3-cell stage and defined the blastomere that cleaved first (named a), distinguished from the sister blastomere that cleaved second (named b), thus rendering an embryo in the 4-cell stage. Subsequent cleavage resulted in a 5-celled embryo; therefore, the blastomere that cleaved to the 5-cell stage first was named either a1 or b1, depending on blastomere origin (a or b). Successive cleavages led to the 6-, 7-, and 8-cell stages and defined the corresponding a/b2, a/b3, and a/b4 blastomeres in the 4-cell stage. Thus, the illustrated six blastomere cleavage patterns were possible. On the right of the figure are the mathematical expressions required to calculate the cell cycle durations of each blastomere, according to the embryo model. Fertility and Sterility 2015 104, 728-735DOI: (10.1016/j.fertnstert.2015.05.024) Copyright © 2015 American Society for Reproductive Medicine Terms and Conditions