The human embryo following biopsy on day 5 versus day 3: viability, ultrastructure and spindle/chromosome configurations

Abstract

Research Question

: Are there any differences in viability, spindle abnormalities and mitochondrial and other organelles' structure amongst embryos biopsied on day3 vs day5 before and after vitrification?

Design

: 240 Day3 biopsied embryos that developed to blastocysts but were rejected for transfer following PGT-M (n=115) or PGT-A (n=125) were divided into 2 groups: A) 120 blastocysts treated for Viability, Spindle/ Chromosomes Configurations (SCC) analysis and TEM analysis (fresh n=20, n=20, n=20 and following vitrification/warming n=20, n=20, n=20), B) 120 embryos were rebiopsied at the blastocyst stage and treated for Viability, SCC and TEM analysis (fresh n=20, n=20, n=20 and following vitrification/warming n=20, n=20, n=20). Also, 60 vitrified blastocysts biopsied only on Day5 that were rejected for transfer following PGT-M (n=6) or PGT-A (n= 54) were treated following warming for Viability (n=20), SCC (n=20) and TEM analysis (n=20).

Results

: No differences are observed in spindle/ chromosomes configurations and ultrastructure between embryos biopsied on day5 and day3 but following vitrification higher numbers of abnormal spindles, distension of mitochondria, multivesicular bodies, lipofuscin droplets, altered cell junctions and occasionally excessive accumulation of glycogen granules were evident. The fresh day 3 biopsied group also had a lower incidence of damaged (PI stained) cells compared to the fresh day3+5 (p= 0.02) and the vitrified day 5 (p=0.001) biopsied groups.

Conclusions

: Biopsies on Day5 and Day3 do not adversely affect embryo viability, spindle/ chromosomes configurations, and ultrastructure, although following vitrification minimal embryo quality dependent increase in spindle abnormalities and cell damage are observed.

Key Message

: Biopsy on Day 5 and Day3 does not adversely affect cell viability, cytoskeleton, ultrastructure and development of embryos, although following vitrification minimal but yet statistically significant increase in spindle abnormalities, and cell damage are observed.