Takuya Sato and his colleagues at Yokohama City University, Japan, extracted
germ cells (cells that gives rise to gametes) from the testes of newborn mice that had not yet begun producing sperm. This was placed into an
agarose gel soaked in
nourishing chemicals and hormones such as
fetal bovine serum and
testosterone. The mice had been genetically engineered so that a protein only present in fully grown sperm cells would turn green. One month later, the team spotted that almost half their samples had turned green. The sperm were then fused with eggs to create healthy embryos, which were implanted into females to produce healthy offspring which were able to mate and give birth to their own pups.
Another similar study took place in Kyoto University, again, Japan where a research team was able to turn a mouse embryonic stem cell into
sperm precursor cells (also known as primordial germ cells). The embryonic stem cells were cultured in cocktails of growth-factors and proteins, which lead to
epiblast-like cells that could be used to create primordial germ cells. These were then implanted into the testes of male mice, where they further matured into sperm cells.
If these technique can be repeated with human sperm, it may lead to new methods of treating infertile men.
