part of part of in taxon results in development of in utero embryonic development placenta development embryonic placenta development GO:0001892 The embryonically driven process whose specific outcome is the progression of the placenta over time, from its formation to the mature structure. The placenta is an organ of metabolic interchange between fetus and mother, partly of embryonic origin and partly of maternal origin. fetal placenta development embryonic organ development anatomical structure development Theria <mammals> chorionic villus