Timing of genomic imprinting
cummins at possum.murdoch.edu.au
Tue Jan 11 21:26:34 EST 1994
Does anyone have any information on when genomic imprinting is
completed in mammalian spermatogenesis? There's a report of
fertilization by fusion of round spermatids with oocytes (mouse,
hamster) but so far no successful embryo development.
This question is relevant to current techniques using micro-assisted
human fertilization by intracytoplasmic sperm injection (ICSI) in
cases of severe male infertility. There are already reports of
fertilization using very immature sperm from the rete testis. Poor
chromatin condensation is significantly associated with male
infertility, and if imprinting is not completed until after the second
meiotic division this could lead to problems in embryo development.
In addition, there are strong associations between epididymal blockage
( a common indication used for carrying out ICSI) and cystic fibrosis,
which is a bit worrying.
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