Simple, efficient and successful vitrification of bovine blastocysts using electron microscope grids.
This study demonstrates that higher survival of vitrified-thawed bovine blastocysts can be obtained using electron microscope (EM) grids as embryo containers at freezing, rather than plastic straws. In-vitro produced day 7 bovine blastocysts after in-vitro fertilization (IVF) were vitrified on grids or in straws with EFS40 freezing solution and their survival after thawing was compared. Embryo survival was assessed as re-expanded and hatched rates at 24 and 48 h after thawing respectively. When the effects of exposure to vitrification solution and chilling injury from the freezing procedure were examined, embryo survival in the exposure group (24 h: 100, 48 h: 73.3%) was not different compared with that in the control group (100, 84.4%). After vitrification, the hatched rate of the EM grid group 48 h after thawing (67.8%) was significantly higher than that of the straw group (53.3%) (P < 0.05). Fast developing embryos (expanded blastocyst and early hatching blastocyst stage) showed better resistance to freezing than delayed ones (early blastocyst stage), irrespective of embryo containers (early: 24 h, 57.1 and 48 h, 24.4%; expanded: 84.7 and 60.6%; early hatching: 91.7 and 80.0%) (P < 0.001). When using expanded and early hatching blastocysts, embryo survival rates in the vitrification-EM grid group (67.8, 95.0% respectively) were significantly higher than that of the vitrification-straw group (53.0, 65.0%) at 48 h.
Park
S P
SP
Maria Infertility Medical Institute, 103-11 Sinseol-dong Dongdaemun-Gu, Seoul, Korea.
Kim
E Y
EY
Kim
D I
DI
Park
N H
NH
Won
Y S
YS
Yoon
S H
SH
Chung
K S
KS
Lim
J H
JH
D000818:Animals; D001755:Blastocyst / Q000502:physiology*; D002417:Cattle; D015925:Cryopreservation / Q000379:methods*; D005314:Embryonic and Fetal Development; D005260:Female; D005307:Fertilization in Vitro / Q000662:veterinary; D006358:Hot Temperature; D008854:Microscopy, Electron / Q000295:instrumentation*; D009584:Nitrogen
D009584:Nitrogen