The OPT technique used to generate the HDBR 3D models relies on the autofluorescence of the fixed embryonic tissue. In some samples the blood fluoresces brightly, allowing us to see the developing blood vessels very clearly.

In the movie below, the arteries in the head of the N317 model have been manually defined and are displayed in different colours as follows: internal carotid artery – red, anterior cerebral artery – orange, middle cerebral artery – yellow, posterior communicating artery – bright green, anterior communicating artery – brown, posterior cerebral artery – dark green, superior cerebellar artery – light blue, basilar artery – blue, pontine arteries – dark blue, anterior inferior cerebellar artery – light purple, vertebral artery – pink, ophthalmic - magenta, unidentified arteries- white.