Figure S7.

Assembly of the external carotid and ophthalmic arteries and 3D visualization of human embryonic structures with Verge3D, related to Figures 1, 6, and 7

(A) In a PCW5.6 specimen, the left common carotid artery (CCA) primitively divides into an internal carotid artery (ICA) and a ventral pharyngeal artery (VPA), the future stem of the external carotid artery (ECA), not to be confused with the adult ascending pharyngeal artery. Note that the CCA is still connected to the aorta by a putative carotid duct (pCD) remnant. The ICA gives rise to the transient stapedial artery (SA), passing through the stapedial ring obturator foramen (well depicted with SOX9 staining in a PCW7 specimen in B). At PCW5.6 (A), the nascent SA divides into a lower maxillomandibular division (MMD) and an upper supraorbital division (SOD). The ICA (well depicted in C) gives rise to a primitive dorsal ophthalmic artery (PDOA), proximal to the posterior communicating artery (PCom), and a distal primitive ventral ophthalmic artery (PVOA).

(B) Foreshadowing future reconfigurations, at age PCW7, the VPA has anastomosed with the lower division of the stapedial artery, acquiring the internal maxillary artery (IMA) in the process, and the ophthalmic artery has anastomosed with the upper division of the stapedial artery, acquiring its extraocular orbital branches (SOD). The persistent channel between the two (white vessel) is the future middle meningeal artery, connected to the ophthalmic artery by the so-called sphenoidal anastomosis (SpA, well depicted in D). The inset shows an unidentified branch of the ICA, proximal to the origin of the SA, speculatively related to the embryology of the ascending pharyngeal artery and warranting further exploration.

(A and C) Interestingly and contrary to a common misconception, the PVOA is not a branch of the anterior cerebral artery but rather arises from ICA cranial division (ICA CD), opposite to the emergence of the anterior choroidal artery (AChoA) and proximal to the origin of the middle cerebral artery (MCA). The PDOA branches into a temporociliary artery (TCilA) and a hyaloid artery (HA) penetrating the optic nerve. The PVOA terminates as a nasociliary artery (NCilA).

(D) At PCW7 (superior view), the stem of the definitive ophthalmic artery gives rise to both nasociliary and temporociliary arteries as well as the hyaloid artery.

(E–H) PLVAP immuno-staining of four PCW5.4 to PCW10.4 eyes showing the choroid (brown, fed by the ciliary arteries) and hyaloid (blue, fed by the hyaloid artery) vasculatures. The ocular growth series between PCW5.4 and PCW10.4 specimens demonstrates the maturation of the vasa hyaloidea propria (VHP), the tunica vasculosa lentis (TVL), and the pupillary membrane (PM) vessels. Establishment of the PM vascular coverage was the last element of the hyaloid vasculature to appear between PCW7 and PCW8.1.

(I–L) (I and L) Visualization of human embryonic structures, through screenshots of 3D models of two PCW7 human embryo visualized in Verge3D web interface. Structures were immunostained with Collagen 2 (I and J) SMA, PLVAP, and Sox9 (K and L), segmented and 3D meshes were generated. (I) Frontal view of the whole embryo presumptive skeleton. (J) Lateral view of the head and neck presumptive skeleton. (K) shows all segmented structures pseudocolored through the semi-transparent embryo surface. (L) shows the vertebral arteries in relation to the cervical spine (the embryo surface is deleted).

Scale bars: 500 μm in (A), (C), and (E)–(H) and 1 mm in (B), (D), and (L).