MSX1-positive cells were observed in the eye section of an 8-week-old human embryo in the retina and choroid (Figure 4a), in retinoblastoma (retina, choroid, and tumor tissue) (Figure 4b), in spindle melanoma (retina, choroid, and tumor tissue), in myxoid only in tumor tissue (Figure 4d), and in epithelioid melanoma in the retina and choroid. The gene discussed is MSX1; the disease is epithelioid cell melanoma.