TECHNIQUE FOR REPETITIVE RECORDING FROM FETAL RESPIRATORY NEURONS

We developed a new method for repetitive recording of medullary neuron s in fetal sheep in situ. The technique involves chronically fixing th e fetal head to the flank of the ewe by way of a Teflon plate that has a removable window. This window allows direct access of a recording e lectrode to the floor of the fourth ventricle of the fetus. In four of six fetuses, repetitive recordings lasting 3-4 h were possible for up to 6 days. By operating on younger fetuses and with care, this time s pan could be extended. This novel method should be useful in the futur e for extracellular and intracellular recordings of neurons in the dev eloping fetus without disturbing the fetal state and for the study of putative neurotransmitters during development with iontophoretic techn iques.