治疗不孕症时,常继之出现缩短黄体期致胚胎植入失败、妊娠率降低等现象,其机理也还很少阐明。在程渭玉等[12]的研究中也表明HCG对胚胎的毒性,且存在时间、剂量依赖关系。试验添加不同浓度的HCG使4-细胞胚胎及其后的各阶段胚胎发育下降尤为明显,并且未发现发育到囊胚阶段的胚胎。
PMSG在母马妊娠38~40d时可以检测出,60d时达到高峰,而在120d时开始下降,170d时下降到检测不出的水平;HCG在非孕妇女处于较低水平,在胚胎发育早期也处于低水平,在妊娠第2周以后显著增加。近来也有学者研究认为胚胎体外发育与激素PMSG、HCG存在关联[13],其他激素也可能影响到胚胎的质量[14-16]。在辅助生殖和超数排卵过程中,需要使用高浓度的PMSG和HCG,在血中二者的浓度高于正常值。在培养体系中添加高浓度的PMSG和HCG,调查其对早期胚胎发育的影响,研究发现胚胎暴露在高浓度的PMSG和HCG降低了胚胎体外发育到各阶段的比例,尤其是明显降低了囊胚的发生率,而HCG对胚胎体外发育的影响似乎更大。由于所调查的样本还较小,其具体情况和具体机制等尚需要深入研究,下一步将扩大试验次数并深入研究多种激素的联合作用对胚胎体外早期发育的影响。
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