title: Postthaw survival of in vitro-produced bovine blastocysts loaded onto the inner surface of a plastic vitrification straw.
abstract: In this study, we investigated whether vitrification of an embryo by attachment to the inner surface of a plastic straw, which requires a small volume of vitrification solution, improves the survival of thawed embryos. In vitro-produced Korean native cattle blastocysts were randomly assigned into four groups: (1) blastocysts attached to the inner surface of a plastic straw (aV); (2) blastocysts loaded into the column of a plastic straw (cV); (3) blastocysts directly dropped into liquid nitrogen (dV); and (4) nonvitrified blastocysts (control). The postthaw recovery rate did not significantly differ among the aV, dV, and cV groups (98.3% vs. 81.5% vs. 91.4%). The postthaw survival rate was greater in the control, aV, and dV groups than in the cV group (100%, 87.7%, and 81.8% vs. 26.4%, P < 0.05), but did not significantly differ among the control, aV, and dV groups. The total number of cells per blastocyst did not significantly differ among the groups (134.4 ± 38.9 in control vs. 114 ± 48.1 in aV, 105.6 ± 33.9 in dV, and 102 ± 35.1 in cV group). However, the number of apoptotic cells per blastocyst was higher in the dV and cV groups than in the control group (10.9 ± 9.6 and 14.5 ± 9.5 vs. 0.4 ± 1.4; P < 0.05), but did not significantly differ between the control and aV groups (0.4 ± 1.4 vs. 6.6 ± 9.5). In addition, the blastocoel of each blastocyst was left intact or was mechanically punctured to reduce its volume, and the blastocysts were then vitrified using the aV method. At 12 hours after thawing, the re-expansion rate did not significantly differ among the control, punctured aV, and nonpunctured aV groups (93.3% vs. 85.2% vs. 82.8%). However, at 24 hours after thawing, the hatching rate was greater in the control and punctured aV groups than in the nonpunctured aV group (75% and 62.9% vs. 37.1%; P < 0.05). The total number of cells per blastocyst was greater in the control group than in the nonpunctured aV group (143 ± 37.2 vs. 94.5 ± 18.6; P < 0.05), but did not significantly differ between the control and punctured aV groups (143 ± 37.2 vs. 119.4 ± 19.7). The number of apoptotic cells per blastocyst was greater in the nonpunctured aV group than in the control and punctured aV groups (11.3 ± 6.1 vs. 5.9 ± 5.8 and 6.3 ± 4.4; P < 0.05). Taken together, the data show that the aV method improved the survival and quality of vitrified-thawed blastocysts. Furthermore, puncture of the blastocoel increased the hatching rate and reduced the number of apoptotic cells in vitrified-thawed blastocysts generated using the aV method.
authors.affiliation: Department of Animal Science, Division of Applied Life Science (BK21), Jinju, GyeongNam Province, Republic of Korea.
authors.forename: A-Na
authors.initials: AN
authors.lastname: Ha
authors.affiliation: Department of Animal Science, Division of Applied Life Science (BK21), Jinju, GyeongNam Province, Republic of Korea.
authors.forename: Han-Seul
authors.initials: HS
authors.lastname: Park
authors.affiliation: Department of Animal Science, Division of Applied Life Science (BK21), Jinju, GyeongNam Province, Republic of Korea.
authors.forename: Jong-In
authors.initials: JI
authors.lastname: Jin
authors.affiliation: Department of Animal Science, Division of Applied Life Science (BK21), Jinju, GyeongNam Province, Republic of Korea.
authors.forename: Sang-Ho
authors.initials: SH
authors.lastname: Lee
authors.affiliation: Department of Animal Science and Biotechnology, Sangji Youngseo College, Wonju, Republic of Korea.
authors.forename: Dae-Hwan
authors.initials: DH
authors.lastname: Ko
authors.affiliation: Division of Life Science, College of Natural Sciences, Kyungpook National University, Daegu, Republic of Korea.
authors.forename: Dong-Suk
authors.initials: DS
authors.lastname: Lee
authors.affiliation: Animal, Dairy, and Veterinary Sciences Department, School of Veterinary Medicine, Center for Integrated Biosystems, Utah State University, Logan, Utah, USA.
authors.forename: Kenneth L
authors.initials: KL
authors.lastname: White
authors.affiliation: Department of Animal Science, Division of Applied Life Science (BK21), Jinju, GyeongNam Province, Republic of Korea; Institute of Agricultural and Life Science, Gyeongsang National University, Jinju, GyeongNam Province, Republic of Korea. Electronic address: ikong7900@gmail.com.
authors.forename: Il-Keun
authors.initials: IK
authors.lastname: Kong
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000502:physiology*; D002417:Cattle / Q000196:embryology*; D015925:Cryopreservation / Q000295:instrumentation / Q000379:methods / Q000662:veterinary; D005307:Fertilization in Vitro / Q000662:veterinary; D010969:Plastics; D058989:Vitrification
chemical_list: D010969:Plastics
keywords: Attachment of embryo to a plastic straw; Cattle; In vitro-produced embryo; Postthaw survival; Straw loading method