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The hatching process of equine embryos in vitro
Author(s) -
HOCHI S.,
BRAUN J.,
OGURI N.
Publication year - 1993
Publication title -
equine veterinary journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.82
H-Index - 87
eISSN - 2042-3306
pISSN - 0425-1644
DOI - 10.1111/j.2042-3306.1993.tb04836.x
Subject(s) - embryo , zona pellucida , andrology , hatching , biology , blastocyst , anatomy , embryo culture , embryogenesis , oocyte , genetics , medicine , zoology
Summary Blastocysts (5 unexpanded, 5 expanding, 2 hatched) were recovered non‐surgically between 144 and 192 h after detection of ovulation. Unexpanded and expanding embryos were cultured (TCM199 + 10% foetal bovine serum) for 10 days. Mean diameter was 168.0 μm for unexpanded and 251.0 μm for expanding blastocysts, respectively. Unexpanded embryos started to hatch from the zona pellucida (ZP) when their diameter reached 405.4 μm (embryonic age 240.0 h). Four embryos squeezed through a small opening in the ZP whereas 1 embryo gradually tore open the ZP. Three embryos completed the hatching process within 96–120 h. In contrast, expanding embryos started to hatch at a mean diameter of 499.8 μm (embryonic age 192.0 h). Four embryos escaped from the ZP within 12 h. One embryo squeezed through the ZP but did not shed the ZP entirely during culture. In‐vitro hatched embryos continued to expand spherically until reaching a maximum mean diameter of 1141.7 μm (unexpanded embryos) and 2765.0 μm (expanding embryos), except for 1 embryo which attached to the bottom of the culture dish. In completely hatched embryos, no capsule could be detected at x200 magnification after staining. Three embryos which did not entirely hatch from the ZP until the end of culture had a capsule remaining inside the ZP. In 1 case, a thin acellular layer was detected in the shed ZP after 0.3% trypsin treatment. Both freshly recovered hatched blastocysts (diameter 640 μm, 697 μm) had a clearly visible capsule around the trophectoderm cells. Equine blastocysts not only lost their zona pellucida but also their capsule during the hatching process in vitro.