NFKB1 and hydrops fetalis: While further details are beyond the scope of the present study, our results suggest a mechanism whereby when the barrier is breached, reductions in adherens junctions impacts the activity of transcription factors such as NFkB, that can directly alter the transcriptional landscape of the HF stem cells in a way that promotes immune cell recruitment, and reduces, but does not overcome, the threshold for proliferation (Figure 8 and Figure 6—figure supplement 2D).