Question

where does chiasmata dissappers

Answer 1

Aneuploidy is the presence of an abnormal number of chromosomes in a cell, for example a human cell having 45 or 47 chromosomes instead of the usual 46.[1][2] It does not include a difference of one or more complete sets of chromosomes. A cell with the correct number of chromosomes is called euploid euploidy.[1] An extra or missing chromosome is a common cause of genetic disorders, including some human birth defects. Some cancer cells also have abnormal numbers of chromosomes.[3]Aneuploidy originates during cell divisionwhen the chromosomes do not separate properly between the two cells. Most cases of aneuploidy result in miscarriage and the most common extra autosomal chromosomes 

Answer 2

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As prophase I progresses, the synaptonemal complex begins to break down and the chromosomes begin to condense. When the synaptonemal complex is gone, the homologous chromosomes remain attached to each other at the centromere and at chiasmata. The chiasmata remain until anaphase I.