develops from develops into visual primordium primordium Bolwig organ Bolwig organ primordium UBERON:6005830 FBbt:00005830 larval eye primordium P1 BolOrg Bolwig's organ primordium fly_anatomy.ontology Primordium of the embryo that gives rise to the larval Bolwig organ. It develops from the most posterior region of the visual primordium, remaining attached to the surface as the rest of the optic placode becomes internalized during stages 12-13 (Green et al., 1993). It consists of approximately 12 cells, which begin to differentiate into photoreceptors during stage 13 (Green et al., 1993). During stages 15-16, the photoreceptors move out of the epidermis and come to lie attached to the outer lining of the dorsal pouch (Green et al., 1993). anterior ectoderm derivative