Vessel development in the yolk sac is important for the embryo development and the malfunction of which can lead to cardiac dysfunction, embryonic malformation and miscarriage. Although substantial emphasis has been placed on the yolk sac vascular remodeling, no detailed three-dimensional (3D) imaging and quantitative analysis of this process has been described. Herein, we explored the development of the vascular system in the visceral yolk sac (VYS) on E11.5, E12.5 and E13.5 mouse embryos using a home-built large field-of-view (FOV) optical-resolution photoacoustic microscopy (OR-PAM). The results showed that OR-PAM can be used as a label-free imaging tool for studying the 2D/3D morphology changes of the vascular system during organogenesis. In addition, after a quantitative analysis the results showed that the microvascular density in the VYS gradually reduced along with the embryo growth. Vascular density in the VYS of E11.5 mouse embryos was almost 6-fold than that of E13.5. Hovever, the averaged vessel diameter of the entire VYS membrane increased gradually with the development of embryos. This study suggests that OR-PAM is a potential tool for acquiring the hemodynamic parameters of mammalian embryos, which could be further used for studying diseases related with the vascular remodeling such as vascular malformations and heart defects.

卵黄囊中的血管发育对于胚胎发育很重要，而卵黄囊的功能障碍会导致心脏功能障碍，胚胎畸形和流产。尽管已将重点放在卵黄囊血管重塑上，但尚未描述此过程的详细三维（3D）成像和定量分析。本文中，我们使用自制的大视野（FOV）光学分辨率光声探测器，探索了E11.5，E12.5和E13.5小鼠胚胎上的内脏卵黄囊（VYS）的血管系统发育显微镜（OR-PAM）。结果表明，OR-PAM可以用作研究器官形成过程中血管系统2D / 3D形态变化的无标记成像工具。此外，经过定量分析后，结果表明VYS中的微血管密度随着胚胎的生长而逐渐降低。E11.5小鼠胚胎的VYS中的血管密度几乎是E13.5的6倍。因此，整个VYS膜的平均血管直径随着胚胎的发育逐渐增加。这项研究表明，OR-PAM是获取哺乳动物胚胎血液动力学参数的潜在工具，可进一步用于研究与血管重塑有关的疾病，例如血管畸形和心脏缺陷。