part of part of eye primordium optic pit optic evagination EMAPA:16199 optic sulcus RETIRED_EHDAA2:0001316 (...) an essentially similar sequence of events occurs during the embryonic development of the vertebrate eye. The eye initially develops as a single median evagination of the diencephalon that soon bifurcates to form the paired optic vesicles (reference 1); The first morphological sign of eye development in vertebrates is the bilateral evagination of diencephalon in the early neurula. In mammals, this is marked by the appearance of the optic pit, whereas in fish and amphibians a bulging of the optic primordia is observed. Continued evagination of the optic primordia leads to the formation of the optic vesicles (reference 2).[well established][VHOG] EMAPA:16325 the pit deepens to form the optic vesicle. EHDAA:944 UBERON:0006270 EHDAA2:0004433 A small indentation in the central part of the optic placode. [157-169, Mueller_F_and_ObRahilly_R, The_first_appearance_of_the_neural_tube_and_optic_primordium_in_the_human_embryo_at_stage_10._Anatomy_and_Embryology_(1985)_172][VHOG] A small indentation in the central part of the optic placode. VHOG:0001162 surface groove