The oocyte and human embryo in the early stages of development are surrounded by a pellucid zone (Lat. zona pellucida, ZP). A fertilized oocyte becomes an embryo which is still under the protection of the pellucid zone for 5-7 days of development. By the end of this period, the breakage of the membrane and the release of the embryo begins. This event in embryo development is indicated by the term “hatching”. Only after that the embryo obtains an ability to contact with cells of the endometrium and to be implanted. However, embryos do not always successfully leave the pellucid zone. So, in women older than 38, there is an intense induration of the pellucid zone. Cryopreservation of oocytes and embryos also affects pellucid zone glycoproteins, which leads to its induration. All this can impede the process of natural hatching and thus prevent the embryo from attaching to the uterus wall. Assisted hatching (laser micromanipulation of dissection of embryo zona pellucida) is used in order to solve this problem.