Morphogenesis-Mediated Morphogen Transport

Embryogenesis entails development of an embryo's form and the diversification of its cells' fates. In morphogenesis, tissues grow, stretch, and flow. In patterning, cells communicate their relative positions via morphogens and coordinate their fate decisions, a function of their morphogen exposure over time. While often studied separately, morphogenesis and patterning can unfold simultaneously, especially in early development. Patterning paradigms for static tissues do not account for how cell movements influence cell-cell communication and fate coordination. We present a mathematical framework for morphogen exposure dynamics in reference frames moving with cells (Lagrangian coordinates) in complex tissue flows. Our framework provides insights into the generative role of morphogenesis in morphogen gradient formation, implicating attractors and repellers in multicellular flows as enhancers and barriers to cell-cell communication. We formalize these effects by defining "Embryological Light Cones," the sets of cells whose signals can reach each other over different time intervals during development. We apply this framework to chick gastrulation data.