has part has part has_part characteristic of has modifier retinal rod cell abnormal retina rod cell morphology retina photoreceptor degeneration retina rod cell degeneration MPheno.ontology retinal rod cell degeneration MP:0008451 a retrogressive impairment of function or destruction of one of the photoreceptor cell types of the vertebrate retina, in which the photopigment is in stacks of membranous disks separate from the outer cell membrane abnormal degenerate