Decoupling from yolk sac is required for extraembryonic tissue spreading in the scuttle fly Megaselia abdita
Francesca Caroti,
Everardo González Avalos,
Viola Noeske,
Paula González Avalos,
Dimitri Kromm,
Maike Wosch,
Lucas Schütz,
Lars Hufnagel,
Steffen Lemke
Affiliations
Francesca Caroti
Centre for Organismal Studies Heidelberg, Heidelberg, Germany
Everardo González Avalos
Centre for Organismal Studies Heidelberg, Heidelberg, Germany
Viola Noeske
Centre for Organismal Studies Heidelberg, Heidelberg, Germany
Paula González Avalos
Centre for Organismal Studies Heidelberg, Heidelberg, Germany
Dimitri Kromm
European Molecular Biology Laboratory, Heidelberg, Germany; Collaboration for joint PhD degree between EMBL and Heidelberg University, Faculty of Biosciences, Heidelberg University, Heidelberg, Germany
Maike Wosch
Centre for Organismal Studies Heidelberg, Heidelberg, Germany
Lucas Schütz
Centre for Organismal Studies Heidelberg, Heidelberg, Germany
Lars Hufnagel
European Molecular Biology Laboratory, Heidelberg, Germany
Extraembryonic tissues contribute to animal development, which often entails spreading over embryo or yolk. Apart from changes in cell shape, the requirements for this tissue spreading are not well understood. Here, we analyze spreading of the extraembryonic serosa in the scuttle fly Megaselia abdita. The serosa forms from a columnar blastoderm anlage, becomes a squamous epithelium, and eventually spreads over the embryo proper. We describe the dynamics of this process in long-term, whole-embryo time-lapse recordings, demonstrating that free serosa spreading is preceded by a prolonged pause in tissue expansion. Closer examination of this pause reveals mechanical coupling to the underlying yolk sac, which is later released. We find mechanical coupling prolonged and serosa spreading impaired after knockdown of M. abdita Matrix metalloprotease 1. We conclude that tissue–tissue interactions provide a critical functional element to constrain spreading epithelia.
