ARTIFICIAL REMOVAL OF ZONA PELLUCIDA AT THE PRONUCLEAR STAGE (ZP-FREE CULTURE) DECREASES THE INCIDENCE OF ABERRANT DIVISION AT THE FIRST CLEAVAGE

Abstract

Aberrant division, also known as the direct cleavage (DC), often occurs in human zygotes and is known to adversely affect the implantation rate. To date published data show that the incidence of DC at the first cleavage is approximately 14%. Moreover, studies from our clinic have previously demonstrated that the incidence of DC at the first cleavage is 18.6% (952/5,121). Recently, the ZP-free culture has been conducted in our clinical settings, and the rate of good quality embryos and the blastocyst development are improved by this new culture method. However, how the ZP-free culture method affects the subsequent embryo development has not yet been fully clarified. This study aims to determine if the ZP-free culture method affects the incidence of aberrant division at the early cleavage.