Science produces fascinating puzzles: why is there such a range of placental structures when other mammalian organs are so structurally uniform ? Why and how did the different placental structures evolve ? Comparative placental studies can facilitate the identification of the common factors in placental growth, differentiation and function and their relevance to possible evolutionary pathways. Comparative Placentation is the only book presenting up-to-date data illustrating the great variety of structure but uniform function of vertebrate placentas from fish to man. This information is...