Ultrastructure of preimplantation genetic diagnosis-derived human blastocysts grown in a coculture system after vitrification.
OBJECTIVE
To evaluate ultrastructural features of preimplantation genetic diagnosis (PGD) blastocysts before and after vitrification.


METHODS
Descriptive study of both vitrified and fresh hatching blastocysts.


METHODS
PGD program at the Instituto Universitario, Instituto Valenciano de Infertilidad.


METHODS
Patients undergoing PGD donated their abnormal embryos for research (n = 26).


METHODS
Biopsied embryos were cultured in the presence of human endometrial cells until day 6. Sixteen blastocysts were vitrified. A total of 11 high-scored hatching blastocysts, 6 warmed and 5 fresh, were fixed for ultrastructure.


METHODS
The cytoskeleton structure, type of intercellular junctions, and basic intracellular organelles in trophoectoderm cells and the inner cell mass were analyzed.


RESULTS
Ten of 16 blastocysts (62%) survived the warming process. Six of these showed no signs of cell degeneration and light microscopy revealed similar ultrastructural characteristics to those of controls. However, in trophoectoderm cells from both fresh and cryopreserved blastocysts, a reduced number of tight junctions and the presence of degradation bodies were detected.


CONCLUSIONS
The particular ultrastructural features observed in PGD-derived blastocysts could be related to embryo manipulation and culture conditions. Vitrification does not seem to alter blastocysts, as those that survive hatching do not display detectable cellular alterations when observed through electron microscopy.
Escribá
María-José
MJ
Instituto Universitario IVI, Valencia, Spain. mjescriba@ivi.es
Escobedo-Lucea
Carmen
C
Mercader
Amparo
A
de los Santos
María-José
MJ
Pellicer
Antonio
A
Remohí
José
J
D001755:Blastocyst / Q000648:ultrastructure*; D002478:Cells, Cultured; D018920:Coculture Techniques / Q000379:methods*; D015925:Cryopreservation / Q000379:methods*; D020732:Cytogenetic Analysis; D006801:Humans; D019836:Preimplantation Diagnosis / Q000379:methods*