1928: Spemann's nuclear transfer.
Scientist
Profile:
Hans Spemann
In 1928, Hans Spemann, continuing to
experiment with salamander embryos conducted
the first nuclear transfer experiment in which
he transferred the nucleus of a salamander
embryo cell to a cell without a nucleus.
Using a strand of hair as a noose as he had done in his
1902 splitting of a salamander embryo, Spemann tightened
the noose around a newly fertilized egg cell, forcing the
nucleus to one side and only cytoplasm to the other. No
cell material was allowed to pass between each isolated
side of the cell. Next, Spemann waited as the side with
the nucleus divided and grew until it was a sixteen cell
embryo. Then Spemann loosened the noose, and allowed the
nucleus from one of the embryo cells to slip over into
the cytoplasm on the other side. Finally, Spemann
completely tightened the noose, physically breaking the
ball of cytoplasm and its new nucleus off from the
sixteen cell embryo. From this single cell grew a normal
salamander embryo. The results of this experiment proved
that the nucleus from an early embryo cell was able to
direct the complete growth of a different salamander.
Spemann had created one of the first clones. Spemann published
his results in his 1938 book
"Embryonic Development and Induction" in which he called
for the "fantastical experiment" of cloning
from differentiated or adult cells. 
Overview of
the Nuclear Transfer technique.
Diagram: Spemann's
Nuclear Transfer
Web Link:
Biography of Hans
Spemann
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