Ultrastructure of cryopreserved horse embryos
Wilson, J.M.; Caceci, T.; Potter, G.D.; Kraemer, D.C.
Journal of Reproduction and Fertility. Supplement 35: 405-417
1987
ISSN/ISBN: 0449-3087 PMID: 3479595 Document Number: 301254
Embryos were recovered non-surgically at about day 6 (= 144 h after ovulation) from 15 American Quarter Horse-type mares and were evaluated for morphological changes due to exposure to cryoprotectant and/or cryopreservation. Electronmicroscopy was used to elucidate the fine structure of intracellular organelles which, if damaged, could cause cellular death. The horse embryo does not totally re-expand in 10% glycerol freezing medium, nor will it completely re-expand in the isotonic holding medium following glycerol removal, whether or not the embryo has been frozen. Embryos in this study were frozen by the same protocol as had resulted in a 30% pregnancy rate for frozen embryos. Junctional complexes between trophoblast cells, as well as the plasma and nuclear membranes of trophoblast and inner cell mass (ICM) cells, were intact after treatment in all embryos. Changes in lipid droplets and some mitochondrial degeneration were observed in the ICM cells of the glycerol-treated embryos. The change in the lipid was not observed in the frozen-thawed embryos, but mitochondrial changes were evident in the trophoblast and ICM cells, with the most extensive mitochondrial damage in the ICM cells.