Mammalian reproduction
Reproductive system
Marsupials' reproductive systems differ markedly from those of placental mammals, though it is probably the plesiomorphic condition found in viviparous mammals, including non-placental eutherians. During embryonic development, a choriovitelline placenta forms in all marsupials. In bandicoots, an additional chorioallantoic placenta forms, although it lacks the chorionic villi found in eutherian placentas.
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