Sir for amniocentesis sex determination, v make use of fetal chromosome in amniotic fluid.how does it occur there? Whether amniotic fluid also contain maternal chromosome

Amniotic fluid is basically generated from mothers plasma ( gestational sac) which is then passed into the foetal membrane through pressure difference between gestational sac and amnion sac.As the amniotic fluid is just plasma like in composition, it do not contain any maternal cell or chromosome but it contains few foetal cells which are taken out in amniocentesis process and cultured in lab for analysing the genetic makeup of developing foetus.