H. Laverge et al., FLUORESCENT IN-SITU HYBRIDIZATION ON HUMAN EMBRYOS SHOWING CLEAVAGE ARREST AFTER FREEZING AND THAWING, Human reproduction, 13(2), 1998, pp. 425-429
Our current freezing-thawing policy is to transfer only embryos that c
leave further in the 24 h following thawing, The purpose of our study
was to investigate the incidence of numerical abnormalities for chromo
somes X, Y and 1 in blastomeres of human preimplantation embryos that
survived cryopreservation but did not cleave further after thawing. A
total of 63 embryos surviving a freezing-thawing cycle but not cleavin
g further within 24 h after thawing were screened, Of the 63 screened
embryos that showed cleavage arrest 24 h after thawing, 56 embryos (88
.9%) remained arrested 48 h after thawing and slightly more than half
of these (29/56; 51.8%) showed further deterioration in morphological
quality, Seven embryos (11.1%) showed signs of further cleavage; five
embryos showed additional cleavage of one blastomere and two developed
a blastocoelic cavity, Fluorescent in-situ hybridization (FISH) with
three specific probes for simultaneous detection of chromosomes X, Y a
nd 1 was performed and was successful in 60 out of 63 embryos, Of thes
e successfully labelled embryos, 26 (43.3%) were in the diploid range:
12 (20%) were uniformly diploid for the chromosomes X, Y and 1; three
embryos showed aneuploidy in all their blastomeres (two were XXY-kary
otype and one was monosomy 1) and in 11 embryos nondisjunction was det
ected, Thirteen embryos were categorized as being either haploid, trip
loid, tetraploid or hexaploid, Nine embryos were classified as mosaic
and 12 as being highly abnormal or chaotic, These preliminary results
suggest that a large proportion of embryos that do not cleave further
after freezing and thawing carry chromosomal aberrations, This finding
supports our policy of not transferring cryopreserved embryos which d
o not cleave further 24 h following thawing.