Development of Transport Mechanisms for Sulphate and Iodide in Immature Choroid Plexus*

The time‐course of development of sulphate and iodide transport mechanisms in choroid plexus was studied by measuring uptake of [ 35 S]sulphate and [ 125 I]iodide from an incubating medium by isolated choroid plexuses of foetal and newborn rabbits and cats. Sulphate uptake by choroid plexus was poorly developed in rabbit foetuses just before term, but highly developed in newborn animals. Iodide uptake was already well developed in the most immature foetuses studied.