We report studies of preimplantation human embryo development that correlate time-lapse image analysis and gene expression profiling. By examining a large set of zygotes from in vitro fertilization (IVF), we find that success in progression to the blastocyst stage can be predicted with >93% sensitivity and specificity by measuring three dynamic, noninvasive imaging parameters by day 2 after fertilization, before embryonic genome activation (EGA). These parameters can be reliably monitored by automated image analysis, confirming that successful development follows a set of carefully orchestrated and predictable events. Moreover, we show that imaging phenotypes reflect molecular programs of the embryo and of individual blastomeres. Single-cell gene expression analysis reveals that blastomeres develop cell autonomously, with some cells advancing to EGA and others arresting. These studies indicate that success and failure in human embryo development is largely determined before EGA. Our methods and algorithms may provide an approach for early diagnosis of embryo potential in assisted reproduction.

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Sperm chromatin integrity is vital for successful pregnancy and transmission of genetic material to the offspring. We evaluated chromatin integrity in sperm from 60 infertile men and 7 fertile donors comparing the sperm chromatin structure assay (SCSA), TdT-mediated-dUTP nick end labeling (TUNEL), the sperm chromatin dispersion (SCD) test, and acridine orange staining technique (AOT). The TUNEL and SCD assays showed a strong relationship with the SCSA (r Ͼ .866; P Ͻ .001) for sperm DNA fragmentation, both in infertile men and donors of known fertility. AOT did not show any relationship with SCSA. The breakdown of the DNA fragmentation index (DFI) into 3 categories (Յ15%, Ͼ15%-Ͻ30%, and Ն30%) showed that the SCSA, TUNEL, and SCD test predict the same levels of DNA fragmentation. AOT consistently showed higher levels of DNA fragmentation for each DFI category. DNA fragmentation in sperm between infertile men and donor sperm was significantly different (P Ͻ .05) under SCSA (22.0 Ϯ 1.6 vs 11.8 Ϯ 1.4), TUNEL (19.5 Ϯ 1.3 vs 11.1 Ϯ 0.9) and SCD (20.4 Ϯ 1.3 vs 10.8 Ϯ 1.1), respectively. DNA fragmentation in sperm evaluated by AOT did not differ (P Ͼ .05) between infertile men (31.3 Ϯ 2.4) and donors (32.7 Ϯ 4.8). AOT showed extreme variations for sperm DNA fragmentation in semen from both infertile men and donors. The problems of indistinct colors, rapid fading, and the heterogeneous staining were also faced. In conclusion, SCSA, TUNEL, and SCD show similar predictive values for DNA fragmentation, and AOT shows variable and increased levels of DNA fragmentation, which makes it of questionable value in clinical practice.

More than 50 years ago Austin and Chang defined mammalian sperm capacitation as a period of time that sperm must reside in the female reproductive tract before they acquire the ability to fertilize oocytes. Since then numerous investigations have attempted to more clearly define the molecules and processes that are a part of capacitation. The data that have provided a more clear definition of capacitation were primarily derived from in vitro experiments. This is particularly true for studies on human sperm capacitation. While ethical constraints have limited an equal balance of in vivo studies there are those data that when coupled with some of the in vitro data allow for the formulation of a biological framework for human sperm capacitation in vivo. This review will put forth the biological basis for human capacitation.