The wings of dppd8/dppd12 mutants do not develop at all, only rudimentary stubs are formed, this can be rescued by expression of Ecol\lexALG.dpp>dpplexAop.cHa.EGFP : the wings of these adults display venation defects (extra vein material at the anterior crossvein, loss of distal part of L4) and the have slightly elongated shape but their sizes are comparable to that of control wings. The wing size of these rescued flies can in turn be reduced again by hindering the spreading of the dpp morphogen: completely blocking it by co-expressing Zzzz\vhhGFP4Ecol\lexAop.morphotrap.ext.T:Disc\RFP-mCherry at the source (i.e. within the dpp expression domain) blocks the wing blade development completely.
Blocking dpp spreading at its source however does not interfere with the uniform proliferation pattern in larval imaginal discs as the density of mitotic cells (pH3-positive) is comparable between the rescue and morphotrap discs. Clonal growth rates are also not generally affected (assessed by utilizing the Raeppli tissue-labelling tool), but in the morphotrap wing discs low numbers of very small clones (1-3) are found next to the A/P boundary and these are not observed in the control discs.
In wing discs where dpp spreading is blocked at the source, the growth of the lateral part of the wing compartments shows similar width increase and similar growth rate as in the control discs with dpp spreading unhindered. However, the proliferation of the medial cell population (marked by low brk) is abolished, so the overall size of wing disc is visibly decreased compared to controls.
Similarly, hindering the dpp spreading at its (anterior) source reduces the size of the posterior wing pouch by more than 60%.