title: Time-lapse monitoring reveals that vitrification increases the frequency of contraction during the pre-hatching stage in mouse embryos.
abstract: Contraction during the blastocyst stage is observed during embryonic development of various mammals, including humans, but the physiological role of this process is not well understood. Using time-lapse monitoring (TLM), we studied the influence of vitrification and contractions on embryonic development in mice. Mouse embryos were cultured at the 2-cell stage. At the 8-cell stage, embryos were randomly divided into a fresh group (FG) and vitrified group (VG) and observed for up to 144 h. Strong contractions (i.e., contractions causing a decrease in volume of more than 20% and expansion of the perivitelline space) occurred significantly more often in unhatched embryos than hatching embryos in both groups. Regarding hatching embryos, contractions in the pre-hatching stage were significantly more frequent in the VG than the FG. Furthermore, mRNA expression levels of genes related to contractions were determined at three time points, the 8-cell stage, early blastocyst stage, and 20 h after blastocoel formation, with quantitative reverse transcription-polymerase chain reaction. There was no significant difference in Hspa1a expression between the FG and VG, but Hspa1a overexpression was observed just after thawing and tended to decrease gradually thereafter in some blastocysts. Furthermore, in the VG, Atp1a1 tended to show higher expression in the strong contraction group than in the weak contraction group. Overall, vitrification is an excellent method for cryopreservation but could increase contractions in the pre-hatching stage and may increase energy demands of the embryo. Observation of contraction by TLM may improve the evaluation of embryo quality.
authors.affiliation: Department of Obstetrics and Gynecology, Graduate School of Medicine, Akita University, Akita 010-8543, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Shimoda
authors.forename: Jin
authors.initials: J
authors.lastname: Kumagai
authors.forename: Mibuki
authors.initials: M
authors.lastname: Anzai
authors.forename: Katsuya
authors.initials: K
authors.lastname: Kabashima
authors.forename: Kazue
authors.initials: K
authors.lastname: Togashi
authors.forename: Yasuko
authors.initials: Y
authors.lastname: Miura
authors.forename: Hiromitsu
authors.initials: H
authors.lastname: Shirasawa
authors.forename: Wataru
authors.initials: W
authors.lastname: Sato
authors.forename: Yukiyo
authors.initials: Y
authors.lastname: Kumazawa
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Terada
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000166:cytology; D006063:Chorionic Gonadotropin / Q000378:metabolism; D015925:Cryopreservation / Q000379:methods; D003470:Culture Media / Q000737:chemistry; D046149:Embryo Culture Techniques; D047108:Embryonic Development / Q000502:physiology; D005260:Female; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D011247:Pregnancy; D011270:Pregnancy, Animal; D012333:RNA, Messenger / Q000378:metabolism; D012984:Software; D013997:Time Factors; D058989:Vitrification
chemical_list: D006063:Chorionic Gonadotropin; D003470:Culture Media; D018840:HSP70 Heat-Shock Proteins; C498550:Hsp70.3 protein, mouse; D012333:RNA, Messenger