Saunders and Gasseling published data in the Journal of Experimental Biology in 1948, showing that reference marks inserted near the rim of the apical border of the wing bud are dispersed throughout the whole forearm of the wing.
This led them to believe that the apical ectoderm may play a role in forming parts of the wing.
 To test this, they removed apical ectoderm from wing buds which yielded deformed wings.
When they removed dorsal ectoderm, normal wings formed.
These results showed that the cells of the apical ectoderm have a precise fate to form specific regions of the wing.
Saunders and Gasseling published data in the Journal of Experimental Biology in 1948, showing that reference marks inserted near the rim of the apical border of the wing bud are dispersed throughout the whole forearm of the wing. This led them to believe that the apical ectoderm may play a role in forming parts of the wing.  To test this, they removed apical ectoderm from wing buds which yielded deformed wings. When they removed dorsal ectoderm, normal wings formed. These results showed that the cells of the apical ectoderm have a precise fate to form specific regions of the wing.
Zone of polarizing activity