Human sperm cytogenetics and the one-cell zygote.

摘要

Human reproductive wastage is known to be a common event. One major cause of embryonic and fetal losses is chromosomal aberrations, identified by karyotyping spontaneous abortion material and in vitro fertilized human embryos. Karyotyping of human gametes has made it possible to document types and frequencies of chromosomal aberrations directly in eggs and sperm themselves. Our studies with human sperm from normal, healthy men support the view that chromosome-specific aneuploidy does in fact occur, and that frequencies of structural chromosomal aberrations appear to be person specific and stable over time. The types of structural aberrations identified suggest that normal human spermiogenesis may be vulnerable to breakage events or precursor lesions leading to such breakage events. After entry into egg cytoplasm and preceding the formation of first-cleavage mitotic chromosomes, the male as well as the female genome replicate their DNA in a pattern qualitatively similar to that in somatic cells. However, at present it is not known what relationship exists between spontaneous chromosome breaks seen at first cleavage and DNA replication activities. Limited data on survivors of radiotherapy lend support to the view that long-term effects on sperm chromosomal integrity can be identified. Studies on sperm cytogenetics thus have the potential for identifying adverse environmental effects on human spermatogenesis as monitored by this well-defined endpoint. 32 refs., 2 figs., 1 tab.