Neighboring Cells as Living Substrates for Guiding Collective Cell Migration during Development

As cells migrate inside the body, they encounter various biochemical and physical cues that provide them with directional guidance. In the past 20 years or so, there has been a significant shift in the effort to understand how physical factors contribute to cellular behaviors. Nevertheless, much of the research has been focused on the interactions between migrating cells and the extracellular matrix in vitro as these are simpler and more accessible models, while neglecting the importance of the cellular environment, which often requires in vivo model systems. With the development of new technology along with the appropriate choice of model organisms, the interesting topic of cell-on-cell interaction during migration is beginning to unravel. In this review, we will take a deep dive into some of the recent results that demonstrate how the biophysics of the cellular environment can impact cell migration, with a strong focus on the use of in vivo model systems, naming the <i>Drosophila</i> border cells, the <i>Xenopus</i> cephalic neural crest, and the zebrafish posterior lateral line primordium.