ABSTRACT
A change in the elasticity and the resistance to dissolution of the mouse zona pellucida (ZP) was quantitatively evaluated at immature germinal vesicle (GV), mature metaphase II (MII) and fertilized pronuclear (PN) stages. Young's modulus of the ZP was measured using a micro tactile sensor (MTS), a highly sensitive resonator-based sensor for a micro scale elasticity measurement. 0.25% α-chymotrypsin was used for the ZP dissolution assay. The results of measuring the ZP elasticity and the dissolution time clearly showed that the ZP softened during oocyte maturation and the ZP hardened after fertilization. The results indicate that the amount of the zona softening can be a criterion to evaluate oocyte quality for the selection of top quality mature oocyte before in vitro fertilization (IVF) treatment.
Subject(s)
Oocytes/chemistry , Oogenesis/physiology , Zona Pellucida/chemistry , Animals , Chymotrypsin , Elasticity , Female , Male , Mice , Mice, Inbred ICRABSTRACT
In this study, we have proposed and demonstrated experimentally a novel monitoring device of single mouse embryo activity after in vitro fertilization (IVF) using a semiconductor-based field effect transistor (FET). The FET biosensor realized to detect it noninvasively, quantitatively, and continuously by change of hydrogen ions with positive charges, which were induced by dissolved carbon dioxide due to cellular respiration activity during cleavage. The electrical signal of FET biosensor should become an effective indication to evaluate objectively single embryo activity as its morphology is observed subjectively after IVF. The platform based on the FET biosensor will contribute to promote elective single embryo transfer (eSET) in human assisted reproductive technology (ART).
Subject(s)
Biosensing Techniques/methods , Single Embryo Transfer/methods , Transistors, Electronic , Animals , Biosensing Techniques/instrumentation , Embryo Culture Techniques/instrumentation , Embryo Culture Techniques/methods , Female , Male , Mice , Mice, Inbred ICR , Pregnancy , Single Embryo Transfer/instrumentationABSTRACT
A change in the elasticity of mouse zona pellucida was quantitatively evaluated during oocyte maturation, fertilization and early embryo development. Young's modulus of zona pellucida of germinal vesicle (GV), metaphase-II (MII), pronuclear (PN), 2cell, 4cell, 8cell, morulae (M) and early blastocyst (EB) stages was measured using a micro tactile sensor (MTS) and a chamber exclusively designed for the measurement. The MTS has very high sensitivity and a deformation of only 5 microm was sufficient to calculate the Young's modulus and the oocyte/embryo maintained its original spherical shape during the measurement. The Young's modulus of GV, MII, PN, 2cell, 4cell, 8cell, M and EB was 22.8+/-10.4 kPa (n=30), 8.26+/-5.22 kPa (n=74), 22.3+/-10.5 kPa (n=66), 13.8+/-3.54 kPa (n=41), 12.6+/-3.34 kPa (n=19), 5.97+/-4.97 kPa (n=6), 1.88+/-1.34 kPa (n=8) and 3.39+/-1.86 kPa (n=4), respectively. Experimental results clearly demonstrated that the mouse zona pellucida hardened following fertilization. Interestingly, once the zona pellucida hardened at the PN stage, it gradually softened as the embryo developed (i.e. it was found that the zona hardening is a transient phenomenon). Furthermore, the zona pellucida of the GV oocyte was as hard as that of the PN embryo and became soft as it matured to the MII stage. In addition, the safety of the MTS measurement for oocytes and embryos was discussed both theoretically and experimentally.
