Cytochemical localization of transport adenosine triphosphatase in the ferret placenta

The distribution of transport adenosine triphosphatase in the ferret placenta was examined cytochemically by light and electron microscopy. The enzyme was detected in the syncytiotrophoblast but was absent from maternal tissues. It appeared to be associated with cytoplasmic processses on syncytiotrophoblast surfaces directly related to foetal or maternal capillaries. The functional significance of transport adenosine triphosphatase is discussed with reference to the transport of solutes between the maternal and foetal circulation across the trophoblast layer.