Summary of ocular vessel origins. (A-C) Schematic illustration of ocular vessel origin. The colors of vessels represent their origins: from the dorsal PMBC - light blue, ventral PMBC - purple and from the HA – red (excluding the CrDI). Blue and purple represent venous identity, red represents arterial identity. (A) Just before superficial vessels grow, the PMBC and CrDI have connected and the HA entered the eye through the optic fissure. (B) The hyaloid system. Vessels are located inside the eye, at a deeper level than vessels shown in C. (C) The completed superficial system. The NRV is red, indicating its arterial identity with a blue core representing its origin from the dorsal PMBC. Arrows in B and C show direction of blood flow. CrDI, cranial division of internal carotid artery; DRV, dorsal retinal vessel; HA, hyaloid artery; HV, hyaloid vein; L, lens; NRV, nasal radial vessel; PMBC, Primordial midbrain channel; SAV, superficial annular vessel; VRV, ventral radial vessel.