Light micrograph (LM) of a section of human placenta, showing chorionic villi and uterus endometrium. Chorionic villi are villi that sprout from the chorion (one of the membranes that exists during pregnancy between the developing fetus and mother) in order to give a maximum area of contact with the maternal blood. Chorionic villi can be sampled to determine chromosomal or genetic disorders in the fetus. Magnification: 10x at 35mm.