Study of the primo-vascular system and location-dependent oxygen levels for a mouse embryo.

The two major circulatory systems, the lymph system and the blood vessel system, play significant roles in controlling embryonic development. The primo-vascular system (PVS) was recently reported as an additional circulatory system in various animals. In this paper, the PVS in a mouse embryo was investigated. The structural characterization of the PVS in the mouse placenta and umbilical cord, which was visualized with the trypan blue staining technique, was focused on. The PVS was well_developed in the mouse placenta area. Using a nanopore-based amperometric oxygen sensor, the oxygen levels at four different areas of the embryonic brain, placenta, blood vessel, and primo-vessel of the PVS were measured. The relatively higher oxygen levels that were measured at the primo-vessels than at the brain and the placenta, while still lower than the oxygen level that was measured at the blood vessels, may suggest a role of PVS in oxygen transport.