The effect of prolonged light-deprivation on the fine structure of planarian photoreceptors.
D000818:Animals; D003624:Darkness; D005123:Eye / Q000166:cytology*; D008854:Microscopy, Electron; D009410:Nerve Degeneration; D009799:Ocular Physiological Phenomena; D011984:Sensory Receptor Cells / Q000166:cytology* / Q000502:physiology; D014419:Turbellaria / Q000166:cytology*