Differentiation of photoreceptor cell elements was observed in five retinoblastomas. These structures were studied by light and electron microscopy. Evidence of glial differentiation could not be found. The observations support the belief that the retinoblastoma is a distinctive neuronal neoplasm.
Ts'o MOM, Fine BS, Zimmerman LE, Vogel MH. Photoreceptor Elements in RetinoblastomaA Preliminary Report. Arch Ophthalmol. 1969;82(1):57-59. doi:10.1001/archopht.1969.00990020059012