Extrusion and removal of lipid from the cytoplasm of porcine oocytes at the germinal vesicle stage: centrifugation under hypertonic conditions influences vitrification.
In the present study, we examined a novel lipid removal method, centrifugation in solutions made hypertonic by adding 0.27 M sugar. This allowed the lipid to be extruded and removed without the loss of active mitochondria or extra cytoplasm. The type of sugar influenced the proportion of oocytes that could be stratified by centrifugation. Glucose induced the highest extrusion rate of lipid droplets. After vitrification the rates of survival, germinal vesicle breakdown and metaphase II were 30, 26, and 7%, respectively, for lipid-removed GV oocytes; this was significantly higher (P<0.05) than for corresponding vitrified lipid-intact oocytes (2, 0, and 0%, respectively). These results indicated that this method is useful to remove whole lipid droplets without losing mitochondria and improves cryotolerance of porcine GV oocytes.
Hara
Kenshiro
K
Laboratory of Animal Reproduction, Graduate School of Agricultural Science, Tohoku University, Sendai 981-8555, Japan. k-hara@bios.tohoku.ac.jp
Abe
Yasuyuki
Y
Kumada
Nobuyuki
N
Aono
Nobuya
N
Kobayashi
Jin
J
Matsumoto
Hiromichi
H
Sasada
Hiroshi
H
Sato
Eimei
E
D000818:Animals; D002458:Cell Fractionation; D002498:Centrifugation; D015925:Cryopreservation / Q000379:methods / Q000662:veterinary; D003593:Cytoplasm / Q000737:chemistry / Q000648:ultrastructure; D005260:Female; D005950:Glucose Solution, Hypertonic / Q000494:pharmacology*; D008055:Lipids / Q000302:isolation & purification*; D008846:Micromanipulation; D008928:Mitochondria / Q000648:ultrastructure; D009865:Oocytes / Q000737:chemistry* / Q000187:drug effects / Q000648:ultrastructure; D013552:Swine
D005950:Glucose Solution, Hypertonic; D008055:Lipids