The Impact of Biopsy on Human Embryo Developmental Potential during Preimplantation Genetic Diagnosis

Figure 2

Schematic comparison between two different blastocyst biopsy approaches. (a) Day 3 hatching-based blastocyst biopsy entailing the production of a hole in the zona pellucida at the cleavage stage and the biopsy of hatching trophectoderm cells from that hole. Several pitfalls can derive a thicker zona pellucida and a smaller blastocyst since being composed by fewer and bigger trophectoderm cells. Hatching can either occur far from the ICM (a1) or involve the ICM itself impairing the procedure (a2); (b) zona opening with simultaneous blastocyst biopsy approach leaves the embryo undisturbed throughout its in vitro development up to the fully expanded blastocyst stage. Simultaneously opening the zona and retrieving the fragment allow the operator to choose the area and the amount of cells to biopsy. Circle with inner cross indicates laser pulse. TE, trophectoderm; ICM, Inner Cell Mass.

(a)

(b)