Improving the intracytoplasmic sperm injection technique by transmembrane electric potential monitoring

Abstract

Objective: To evaluate electrophysiologic techniques for transmembrane potential measurement during intracytoplasmic sperm injection (ICSI). Design: Mature mouse oocytes were subjected to intracellular measurements of membrane potential using conventional techniques and modifications of the techniques for use with sham ICSI. During the procedure, the actual penetration of the membrane was determined subjectively or objectively with or without monitoring membrane potential. Setting: Academic medical center. Animal(s): Mouse. Intervention(s): Measurement of oocyte membrane potential (Sham ICSI). Main Outcome Measure(s): Detectability of transmembrane potential using different electrodes and comparison of subjective and objective determination of membrane penetration. Result(s): Measurement of the membrane potential with the same glass pipettes used in ICSI means compromise between signal amplitude and compatibility with the conventional ICSI setup. Signal quality is related inversely to the diameter of the injection pipette, and its amplitude decreases as the concentrated electrode filling solution is replaced by physiologic solutions used in ICSI. When successful membrane penetration is suspected by visualization, measuring the potential at the tip of the injection pipette often proves otherwise. Conversely, when membrane penetration is confirmed by detection of transmembrane potential, the procedure may appear subjectively unsuccessful. Conclusion(s): Monitoring of transmembrane potential can be done successfully in conjunction with standard ICSI and has several potential applications.