part of part of optic stalk optic fissure http://upload.wikimedia.org/wikipedia/commons/9/98/Gray865.png Develeopment notes: As the eye starts to develop, a gap opens on the underside of each eye bud. This gap provides a way for the developing eye to be nourished. This gap, called the optic fissure, has to close before the eye is fully developed. Coloboma is the incomplete closer of the optic fissure A break in the continuity of the optic cup where the two sides of the cup meet.[AAO] EHDAA:4759 choroid fissure VHOG:0000655 ZFA:0001284 EHDAA2:0001319 ventral choroidal fissure choroid fissure - optic fissure TAO:0001284 UBERON:0005412 MA:0001305 The folded arrangement of the vertebrate retina and RPE [retinal pigment epithelial] provides an evolutionary explanation for the occurrence of the choroid fissure, as proposed more than a century ago. Early in evolution, before the optic cup invaginated, the axons from retinal ganglion cells would simply have run over the surface of the structure. Hence, one can view the optic nerve as having acted rather like a rope in linking the retina to higher centres: the developing eye cup has simply wrapped around this 'rope', and the developing axons have thereby not needed to penetrate the retina.[well established][VHOG] XAO:0000474 EMAPA:17166 AAO:0011026 optic fissures SCTID:361508004 RETIRED_EHDAA2:0000249 Wikipedia:Choroid_fissure optic stalk fissure Groove that is in the developing ventral optic cup and through which blood vessels pass to the enclosed mesenchyme[ZFA]. a ventral fissure in the developing optic cup through which blood vessels pass to the enclosed mesenchyme[Free online medical dictionary]. optic foramen surface groove ventral part of optic cup