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. Author manuscript; available in PMC: 2013 Mar 1.
Published in final edited form as: Genesis. 2011 Dec 27;50(3):219–234. doi: 10.1002/dvg.20825

Figure 6. Alterations in ABP or PCP randomize heart situs in conjoined twins, regardless of whether polarity is disrupted in one or both twins.

Figure 6

A) Normal heart looping in both twins (green arrows) after injection with XSiamois only. B) Inverted heart looping in both twins (yellow arrows) when XSiamois was paired with DNPar6. C) XSiamois was injected into a single left ventral vegetal blastomere at the 16-cell stage, inducing a secondary organizer (blue circle) directly across from the primary organizer (red circles). A subset of these embryos was injected with DNPar6 at the 1-cell stage, allowing this construct to be expressed in most cells, and then injected with XSiamois at 16-cells. A second subset of embryos was co-injected with both DNPar6 and XSiamois into a single left ventral vegetal blastomere at the 16-cell stage. Inverted heart loops were observed in the induced twins when DNPar6 was injected, regardless of where this construct was introduced. Numbers indicate sample sizes examined, *p=0.01, **p<0.01. D) The same groups were examined as in (C), but this time examining the effects of Vangl2MO. Again, inverted heart loops were observed in the induced twins expressing Vangl2MO, regardless of whether it was injected at 1-cell or co-injected at 16 cell with XSiamois. Numbers indicate sample sizes examined, ***p<0.001.