A monolayer of pigmented epithelium covering the neural retina; develops from the outer of the two layers of the optic cup[ZFA]. the pigmented cell layer just outside the neurosensory retina that nourishes retinal visual cells, and is firmly attached to the underlying choroid and overlying retinal visual cells[WP].
Comment:
[homology-note] "(...) 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. As each optic vesicle grows towards the body surface, its proximal part narrows as the optic stalk, and its distal part invaginates to form a two-layered optic cup. (...) The outer layer of the optic cup becomes the pigment layer of the retina, whereas the inner layer differentiates into the photoreceptive cells and neuronal layers of the retina.[well established][VHOG]" xsd:string {date_retrieved="2012-09-17", external_class="VHOG:0000536", ontology="VHOG", source="ISBN:978-0030223693 Liem KF, Bemis WE, Walker WF, Grande L, Functional Anatomy of the Vertebrates: An Evolutionary Perspective (2001) p.429", source="http://bgee.unil.ch/"}