Changes

[[File:Gray39.png|right|400px|thumb|Diagramatic Representation of the various layers of the placenta (fetal side lower and maternal side upper)]]

[[File:Gray39.png|right|400px|thumb|Diagramatic Representation of the various layers of the placenta (fetal side lower and maternal side upper)]]

==Introduction==

==Introduction==

The formation of the placenta is referred to as the "second" or "embryonic" period of pregnancy (after the implantation period) and describes the establishment of a fully functional placenta. The placenta is an apposition of foetal and parental tissue for the purposes of physiological exchange.  There is little mixing of maternal and foetal blood, and for most purposes the two can be considered as separate.

The placenta signifies the "second" or "embryonic" period of pregnancy (after the implantation period) and describes the establishment of a fully functional placenta. The placenta is an apposition of foetal and parental tissue for the purposes of physiological exchange.  There is little mixing of maternal and foetal blood, and for most purposes the two can be considered as separate.

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