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E T I E N N E
W O L F F
5. Parabiosis between Blastoderms
Parabioses between young blastoderms illustrate a category of
intervention which is practically impossible to achieve in the interior
of the egg. The operation is easily accomplished with the use of Wolff
and Simon's (1955) technique for blastoderm explantation.
The cultivation of blastoderms, whole or in part, can be begun
from the stage which precedes the establishment of circulation, and
continued until the 5 day stage. One can associate in the culture either
two or three whole blastoderms or a whole blastoderm with a part of
another embryo, such as, for example, the posterior region of the trunk
(Fig. 18). When whole embryos are associated, circulatory anastomoses
-*•
c
FIG. 18. Experiments on parabioses in culture in vitro, (a) Two embryos; (b) an embryo and
a caudal part; (c) three embryos. (After Simon, 1960.)
a
b