Application Of Fluorescence In Situ Hybridization (FISH) Of Placental Trophoblast Cells To Detect The Number Of Chromosome

Objective :To investigate placental villi sampling applied to fluorescence in situ hybridization (FISH) for rapid prenatal diagnosis of chromosomal numerical abnormalities .Methods: The preliminary study based on the use of villi from postpartum placental by digestion ,hypotonic ,dissociation ,pre-fixation and fixation, then carried out fluorescence in situ hybridization (FISH) experiment. The experiment used CSP18, CSPX, CSPY probe to detect the corresponding abnormal chromosomal numerical abnormalities with the sex of newborns as control, which is still a preliminary study and follow-up experiments are needed. The experimental steps are as followsâ‘ procedure of samples: In vitro post-partum placenta was sampled in three methods A:sessiors-cutting B: Analog puncture C: placental tissue homogenate .With the experimental specimen slide preparation, next steps of the FISH experiments were proceeded.â‘¡FISH experiments adopted standard procedures of amniotic fluid samples ,some specific steps were changed ,and all changes have been proven to be effective .â‘¢Experimental images and data have been proceeded by cutefish software and recorded in fluorescence in situ hybridization computer.â‘£Image evaluation: The fluorescence signal of the interphase nuclei determines the number of the corresponding chromosomes. The distance between signal points must be greater than the diameter of the same chromosome otherwise will be regarded as noise signal. The number of fluorescent signal points of about 200 interphase nuclei are counted in each sample slide. Results: All 10 cases of samples were normal hybridization signal, no corresponding numerical anomaliitites were found, there was no difference from the clinical control of newborn sex, the achievement ratio was 90.9 %,(11 cases sampled,10 cases succeeded in FISH) one male fetus displayed XX signal of 2 / 200 interphase nuclei which was considered maternal cells mosaicism.Conclusion:â‘ It's possible to detect fetal chromosomal numerical abnomalities,such as the aneuploidy by the application of FISH technology with specimens of placental villi.â‘¡.placental villi FISH technology may detect chromosomal numerical abnormalities for prenatal diagnosis, thereby guiding clinical gestation, have important clinical significance.â‘¢Because of the security problem in sampling and the problem of placental mosaicism, the experiment still need further follow-up researchs before being applied to real clinical work.