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-Inthisstudy,ittakes ~120daysofculture,insteadof~40daysfor development of germ cells in utero, and only 1-2% of the human cells survive and progress to the next stage of development.
-The oogonia were not quite normal in that several processes that have to occur within them to eventually be able to give functional oocytes, namely epigenetic reprogramming and X-chromosome reactivation, were clearly incomplete.
-It will be interesting to know if this is because the mouse granulosa cells can’t fully support human germ cell development or if there are other aspects to the culture system that need tweaking.
-Further work will be essential to improve the efficiency, the maturity and the functionality of the human germ cell development in culture
Conclusions and Future remarks
• Male germ cells and functional sperm have been obtained through mouse ESC and iPS using 2 step protocols (in vitro and in vivo) and fully in vitro.
• Functional oocytes can be obtained from mESC and iPS using 2 step protocol and also fully in vitro.
• Normal healthy offspring with normal methylation patterns of imprinted genes if gametogenesis is resumed in in vivo conditions and recently fully in vitro conditions.
• The use of such human gametes in ART remains a “distant prospect“but nowadays we have more relevant data than 10 years ago.
• Stem cell derived gametes can become a valuable resource for research: germ cell development , epigenetic reprogramming and germline gene modification
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