title: Mouse zona pellucida dynamically changes its elasticity during oocyte maturation, fertilization and early embryo development.
abstract: 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.
authors.affiliation: Nihon University, College of Engineering, NEWCAT Institute, Fukushima, Japan. murayama@ee.ce.nihon-u.ac.jp
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Murayama
authors.forename: Jinji
authors.initials: J
authors.lastname: Mizuno
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Kamakura
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Fueta
authors.forename: Hiroko
authors.initials: H
authors.lastname: Nakamura
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Akaishi
authors.forename: Ken
authors.initials: K
authors.lastname: Anzai
authors.forename: Akihiko
authors.initials: A
authors.lastname: Watanabe
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Inui
authors.forename: Sadao
authors.initials: S
authors.lastname: Omata
mesh_terms: D000818:Animals; D004548:Elasticity; D047108:Embryonic Development / Q000502:physiology*; D005260:Female; D005306:Fertilization / Q000502:physiology*; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D009865:Oocytes / Q000254:growth & development*; D011247:Pregnancy; D015044:Zona Pellucida / Q000502:physiology*