part_of part of part of develops from develops from starts during eye optic vesicle choroid fissure ventral choroidal fissure UBERON:0005412 XAO:0000474 optic fissure Part of the eye that forms during the transition from optic vesicle to optic cup as a groove at the lateroventral edge of the optic vesicle, which expands medially. The ventral edges of the optic vesicle then wrap around the fissure and fuse with one another, ultimately leading to a channel through which blood vessels and optic nerve fibres pass. xenopus_anatomy embryonic structure NF stage 29 and 30