Verónica M Negrón-Pérez1, Peter J Hansen2. 1. Department of Animal Sciences, D. H. Barron Reproductive and Perinatal Biology Research Program and Genetics Institute, University of Florida, Gainesville, Florida, USA. 2. Department of Animal Sciences, D. H. Barron Reproductive and Perinatal Biology Research Program and Genetics Institute, University of Florida, Gainesville, Florida, USA. pjhansen@ufl.edu.
Abstract
PURPOSE: Implantation of the mammalian embryo in the uterus is preceded by escape from the zona pellucida. In some species, hatching from the zona occurs preferentially from one or the other poles of the embryo. The situation for the bovine embryo, in which hatching precedes attachment to the uterus by more than a week, is unclear. The purpose was to describe whether hatching of the bovine embryo from the zona pellucida occurs preferentially from the embryonic or abembryonic pole. METHODS: Bovine blastocysts undergoing hatching were examined by light microscopy (n = 84) and epifluorescence imaging using antibodies for markers of epiblast, hypoblast, and trophectoderm (TE) (n = 26). The location of hatching was classified as being at the embryonic pole, if hatching occurred ipsilateral to the inner cell mass (ICM), or abembryonic, if hatching occurred contralateral to the ICM. RESULTS: A total of 55% of blastocysts exited the zona pellucida through an opening at the embryonic pole. In these cases, 68% of the cells emerging through the zona pellucida were derived from the ICM. The remainder of blastocysts hatched from an opening either contralateral or to the side of the ICM. In these cases, 87% of hatched cells were TE. CONCLUSION: For the bovine embryo, there is nearly equal probability of hatching from the embryonic or abembryonic poles. Given that the surface area of the zona pellucida in contact with the TE overlying the ICM is less than for the remainder of the blastocyst, there is some preference for hatching through the embryonic pole. Thus, the bovine embryo is distinct from the mouse and human, where hatching occurs preferentially at the abembryonic pole.
PURPOSE: Implantation of the mammalian embryo in the uterus is preceded by escape from the zona pellucida. In some species, hatching from the zona occurs preferentially from one or the other poles of the embryo. The situation for the bovine embryo, in which hatching precedes attachment to the uterus by more than a week, is unclear. The purpose was to describe whether hatching of the bovine embryo from the zona pellucida occurs preferentially from the embryonic or abembryonic pole. METHODS:Bovineblastocysts undergoing hatching were examined by light microscopy (n = 84) and epifluorescence imaging using antibodies for markers of epiblast, hypoblast, and trophectoderm (TE) (n = 26). The location of hatching was classified as being at the embryonic pole, if hatching occurred ipsilateral to the inner cell mass (ICM), or abembryonic, if hatching occurred contralateral to the ICM. RESULTS: A total of 55% of blastocysts exited the zona pellucida through an opening at the embryonic pole. In these cases, 68% of the cells emerging through the zona pellucida were derived from the ICM. The remainder of blastocysts hatched from an opening either contralateral or to the side of the ICM. In these cases, 87% of hatched cells were TE. CONCLUSION: For the bovine embryo, there is nearly equal probability of hatching from the embryonic or abembryonic poles. Given that the surface area of the zona pellucida in contact with the TE overlying the ICM is less than for the remainder of the blastocyst, there is some preference for hatching through the embryonic pole. Thus, the bovine embryo is distinct from the mouse and human, where hatching occurs preferentially at the abembryonic pole.
Authors: Anna C Denicol; Jeremy Block; Dale E Kelley; Ky G Pohler; Kyle B Dobbs; Christopher J Mortensen; M Sofia Ortega; Peter J Hansen Journal: FASEB J Date: 2014-05-22 Impact factor: 5.191
Authors: Inna V Ilina; Yulia V Khramova; Anna D Ivanova; Maxim A Filatov; Yuliya Yu Silaeva; Alexey V Deykin; Dmitry S Sitnikov Journal: J Assist Reprod Genet Date: 2020-11-17 Impact factor: 3.412