胚胎选择的侵入性方式

　　The challenge of any technique used for diagnostic purposes is the survival of the specimen that has been studied. Several technologies have been proposed for characterizing the potential of spermatozoa that require fixation and staining of the specimen. Such approaches may give an estimate on an entire sperm cohort from a patient; however, it may not help in picking an individual cell for subsequent injection into an oocyte. Thus, invasive procedures are in general not applicable for single-cell investigations like sperm or oocytes.

　　对于任何用于诊断目的的技术来说，研究样本是否存活至关重要。评估精子细胞的潜力几种技术都需要对样本进行固定和染色。这种方法可以对患者的整个精子群体进行预测;但是，它不适用于挑选单个细胞随后注射到卵母细胞的过程中。因此，侵入性操作通常不适用于精子或卵母细胞等单细胞研究。

　　In contrast, investigating the potential of embryos has been based on the common understanding that the removal of a limited amount of cellular material from an embryo does not negatively influence the overall quality.

　　相反，研究胚胎潜力则基于一个共识，即从胚胎中取出有限数量的细胞样本不会对胚胎整体质量产生负面影响。

　　Chromosomal analysis of embryonic cells

　　胚胎细胞染色体分析

　　In the context of preimplantation genetic screening (PGS) or diagnosis (PGD), chromosomal analysis has been accepted for the biopsy of 1-2 blastomeres at the 8-cell stage for a long time. However, the benefit of PGS was heavily criticized at the time when this technique was mainly performed by blastomere biopsy and fluorescent in-situ hybridization (FISH) for detecting numberical aberrations of the most commonly involved 5-12 chromosomes. This in turn also challenged the assumption of the safety of such an invasive technique. In a study it was shown that embryos that were not biopsied preferentially implanted compared to embryos that were biopsied but not screened by PGS (1). Based on this study, cleavage stage biopsy on day 3 should be considered historical.

　　通过胚胎植入前筛查(PGS)或诊断(PGD)技术，8细胞阶段的胚胎可以取出1-2个卵裂球用于染色体分析。不过，当时这项技术主要通过荧光原位杂交法(FISH)对活检的卵裂球检测最常见的5-12对染色体的变异情况，所以PGS的优势和这种侵入性技术的安全性假设都受到了广泛质疑。有一项研究发现，与活检但未进行PGS筛查的胚胎相比，未进行活检的胚胎更容易植入(1)。因此，不应当再对第3天卵裂期胚胎进行活检。

　　Still, the benefit of PGS is under discussion. The alternative to the problem of embryo mosaicism and the diagnostic limitations of FISH after blastomere biopsy were biopsy of polar body 1/2 or of trophectoderm cells in combination with the diagnosis of all chromosomes (Figure 1).

　　不过，PGS的益处仍然是大家讨论的话题。针对胚胎嵌合体问题和卵裂球活检后FISH诊断局限性的替代方法是对极体1/2或滋养外胚层细胞进行活检并结合染色体分析结果(图1)。

　　The term comprehensive chromosome screening (CCS) has been introduced for techniques like array comparative genomic hybridization (aCGH), quantitative polymerase chain reaction (qPCR), or single nucleotide polymorphism (SNP) microarray analysis.

　　全面染色体筛查(CCS)技术一词指的是例如微阵列基因组杂交法(aCGH)，定量聚合酶链反应法(qPCR)或单核苷酸多态性(SNP)微阵列分析等技术。