The yolk sac vasculature in early avian embryo provides a novel model for the analysis of cancer extravasation

Hematogenous metastasis, a hallmark of cancer cells, involves a complex series of migration steps, including intravasation, circulation, arrest in blood vessels, and trans-endothelial migration (TEM)-the lattar two collectively referred to as extravasation. Among these steps, extravasation poses significant challenges for imaging in amniotes such as humans and mice due to its unpredictable timing and location, which limits our understanding of the underlying cellular and molecular mechanisms. Thus, the development of a novel cancer carrier model with high-resolution imaging capabilities in amniotes is essential. In this study, we investigated the yolk sac vasculature (YSV) of early avian embryos (chickens and quail) as an innovative model for studying extravasation, capitalizing on its superior imaging capabilities. We assessed the YSV structure and applied fluorescent labeling to improve visibility. Following this, cancer cells were introduced into the YSV, and their behavior was monitored, revealing distinct morphologies and dynamics associated with extravasation. Furthermore, the YSV model exhibited a high degree of quantitative precision for extravasation studies and demonstrated potential for drug screening applications. Our findings indicate that the YSV model holds promise as a novel platform for elucidating the cellular and molecular mechanisms involved in cancer metastasis through advanced imaging techniques.