Cohen J
Department of Gynecology and Obstetrics, New York Hospital-Cornell University Medical Center, New York.
J In Vitro Fert Embryo Transf. 1991 Aug;8(4):179-90. doi: 10.1007/BF01130802.
There are benefits as well as drawbacks of zona pellucida breaching. Narrow gaps in the zona may cause disintegration of the hatching trophectoderm, when embryos are cultured in vitro. An increase in the formation of monozygotic twins following micromanipulation may also occur, due to the forced separation of the inner cell mass during blastocyst expulsion in utero. Mouse studies indicate that one or several narrow zona openings (less than 5 microns) are detrimental. Such embryos may become trapped during hatching but may be rescued by drilling an additional larger gap elsewhere on the zona. The use of acidic Tyrode's solution for clinical assisted hatching of eight-cell embryos is currently under investigation. The findings suggest that large holes are efficient for promoting hatching (at least one-fourth of the embryos implanted thus far) and that embryos with unthinned zonae (those with normally the poorest prognosis) benefit mostly from assisted hatching. Results also indicate that embryos with the best zona morphology should be replaced without micromanipulation.
透明带破裂有好处也有坏处。当胚胎在体外培养时，透明带上的窄缝可能会导致孵化滋养外胚层解体。由于子宫内囊胚排出过程中内细胞团的被迫分离，显微操作后单卵双胞胎的形成也可能增加。小鼠研究表明，一个或几个狭窄的透明带开口（小于5微米）是有害的。这样的胚胎在孵化过程中可能会被困住，但可以通过在透明带上的其他位置钻出一个更大的缝隙来挽救。目前正在研究使用酸性台氏液对八细胞胚胎进行临床辅助孵化。研究结果表明，大的孔对于促进孵化是有效的（到目前为止植入的胚胎中至少有四分之一），并且透明带未变薄的胚胎（通常预后最差的那些）从辅助孵化中受益最大。结果还表明，具有最佳透明带形态的胚胎应在不进行显微操作的情况下进行移植。
