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Abstract Embryonic tissues undergoing shape change draw mechanical input from extraembryonic substrates. In avian eggs, the early blastoderm disk is under the tension of the vitelline membrane (VM). Here we report that the chicken VM characteristically downregulates tension and stiffness to facilitate stage-specific embryo morphogenesis. Experimental relaxation of the VM early in development impairs blastoderm expansion, while maintaining VM tension in later stages resists the convergence of the posterior body causing stalled elongation, failure of neural tube closure, and axis rupture. Biochemical and structural analysis shows that VM weakening is associated with the reduction of outer-layer glycoprotein fibers, which is caused by an increasing albumen pH due to CO2 release from the egg. Our results identify a previously unrecognized potential cause of body axis defects through mis-regulation of extraembryonic tissue tension.

The E3 ubiquitin ligases RNF43/ZNRF3 are often mutated in cancer but their precise contribution to liver disease is unknown. Here, the authors show that RNF43/ZNRF3 alterations predispose to liver cancer by controlling the differentiation and lipid metabolic state of hepatocytes.

In addition to paternal genetic material, sperm contributes epigenetic information to the embryo to efficiently support development. Here, the authors demonstrate a homogeneous paternal contribution to epigenetic information via sperm-derived modified histone transmission to the developing vertebrate embryo.

Cell competition is a quality control mechanism to eliminate unfit cells. Here the authors show that physical compaction of less fit cells surrounded by healthy neighbours leads to increased expression of tumour suppressor p53 in the compacted cells, causing cell death.