The embryonal development of the human eye photoreceptors

The development of the photoreceptors of human embryos and fetuses dating from 7 weeks to term were studied. The outer segments of rods and cones began to form at the seventh month. The arrangement of the newly formed discs were not regular, but at term they were arranged parallel to each other and perpendicular to the long axes of the outer segments. At the 9th month, no phagosome containing discs was seen in the pigment epithelial cells, but they were discerned in those of the term fetuses.