Many oval peroxisomes can be seen in normal cytotrophoblast cells of first trimester chorionic villus. The cytotrophoblast also contains glycogen particles, isolated and in flakes, which distinguish these cells from the syncytiotrophoblast (at left in this image). Bars = 1 µm (low magnification), 0.1 µm (high magnification). In some genetic diseases (Zellweger, Infantile Refsum) peroxisomes are absent; this can be diagnosed in chorionic villi.