Chapter 25
Vitrification of Equine In Vivo-Derived Embryos After
Blastocoel Aspiration
Carolina Herrera
Abstract
Embryo cryopreservation is normally performed with great success in species like humans and cattle. The
large size of in vivo-derived equine embryos and the presence of a capsule—impermeable to cryoprotectants—have complicated the use of embryo cryopreservation in equine reproduction. A breakthrough for
this technique was obtained when large equine embryos could be successfully cryopreserved after collapsing
the blastocoel cavity using a micromanipulation system. High pregnancy rates have been obtained when
vitrification is used in combination with embryo collapse.
Key words Equine embryo, Vitrification, Embryo collapse, In vivo-derived embryo
1 Introduction
The reasons for the low success rates of cryopreserving large
(>300 μm in diameter) in vivo-derived equine embryos are the
large embryonic size and blastocoel volume [1], the presence of
an embryo capsule [2, 3], and cryopreservation techniques used in
other species like cattle or humans which do not fulfill the demands
of equine blastocysts. A major step regarding successful cryopreservation of embryos >300 mm in diameter was achieved by Choi
et al. [1], who collapsed the blastocoel cavity prior to vitrification.
This was done by the puncture of the blastocyst and aspiration of
the blastocoel fluid. Since then, other authors have also reported
similar results collapsing the embryos prior to vitrification
[4, 5]. The method described in this protocol, the preparation of
hemistraws, and the vitrification and warming solutions used are
adapted from previous work [6, 7].
Willem F. Wolkers and Harrie ¨ tte Oldenhof (eds.), Cryopreservation and Freeze-Drying Protocols, Methods in Molecular Biology,
vol. 2180, https://doi.org/10.1007/978-1-0716-0783-1_25, © Springer Science+Business Media, LLC, part of Springer Nature 2021
517
Vitrification of Equine In Vivo-Derived Embryos After
Blastocoel Aspiration
Carolina Herrera
Abstract
Embryo cryopreservation is normally performed with great success in species like humans and cattle. The
large size of in vivo-derived equine embryos and the presence of a capsule—impermeable to cryoprotectants—have complicated the use of embryo cryopreservation in equine reproduction. A breakthrough for
this technique was obtained when large equine embryos could be successfully cryopreserved after collapsing
the blastocoel cavity using a micromanipulation system. High pregnancy rates have been obtained when
vitrification is used in combination with embryo collapse.
Key words Equine embryo, Vitrification, Embryo collapse, In vivo-derived embryo
1 Introduction
The reasons for the low success rates of cryopreserving large
(>300 μm in diameter) in vivo-derived equine embryos are the
large embryonic size and blastocoel volume [1], the presence of
an embryo capsule [2, 3], and cryopreservation techniques used in
other species like cattle or humans which do not fulfill the demands
of equine blastocysts. A major step regarding successful cryopreservation of embryos >300 mm in diameter was achieved by Choi
et al. [1], who collapsed the blastocoel cavity prior to vitrification.
This was done by the puncture of the blastocyst and aspiration of
the blastocoel fluid. Since then, other authors have also reported
similar results collapsing the embryos prior to vitrification
[4, 5]. The method described in this protocol, the preparation of
hemistraws, and the vitrification and warming solutions used are
adapted from previous work [6, 7].
Willem F. Wolkers and Harrie ¨ tte Oldenhof (eds.), Cryopreservation and Freeze-Drying Protocols, Methods in Molecular Biology,
vol. 2180, https://doi.org/10.1007/978-1-0716-0783-1_25, © Springer Science+Business Media, LLC, part of Springer Nature 2021
517