A method for tissue bioassay comprising the steps of placing in the vagina of a female mammal an elongated probe having at least two electrodes positioned close to an insertion end of the probe, none of the electrodes extending around the entire periphery of said probe and at least one of then being metallic, applying across the electrodes an alternating voltage of relatively low peak-to-peak amplitude, measuring across the electrodes a value representative of the phase of the reproductive cycle of the female or the hormonal status of the fornix epitheliurn, and comparing that value with at least one reference value. A probe for practicing this method also is disclosed.