Numerical assessment of chromosomes--Technology ??

 

How to perform numerical asessmement of chromosomes?? :-The chromosome analysis can be done either by 1) cell culture (traditional karyotyping)-This is one of the cytogenetic study. or 2) FISH :  by more recently FISH method (Fluorescent  In situ Hybridization).In FISH method  Fluorescent probe is used on the nuclei of amniocytes and if there is evidence of 1) one signal means that the said nucleus is having monosomy ( after using Fluorescent probe), 2) two signals means euploid nucleus and if 3)  some nuclei reveals three florescent signals it means that the said nucleus is having  trisomy..

FISH:- Usually there are five DNA probes(probes with Fluoro Chrome) : This is one of the DNA study. used like 1) LS-1--21,    2) CEP-18,    3)  LS-1-13 4 & 5 ) CEP- two Sex chromatins    . The cells which shows two different signals after FISH procedure means normal cells

 i. e diploid chromosome with no alteration in number of total chromosomes. Usually five chromosomes are studied in nuclei like amniocytes. These are Chr 21, 13, 18 and two sex chromosomes. Thus these tests of FISH will detect trisomy or monosomy.