title: Membrane permeability characteristics of bovine oocytes and development of a step-wise cryoprotectant adding and diluting protocol.
abstract: Membrane permeability is very helpful for the optimization of effective cryopreservation protocols. In this study, experiments were performed to determine these characteristics for immature (germinal vesicle (GV)) and in vitro matured (metaphase II (MII)) bovine oocytes within 4-37 degrees C, and a new step-wise adding and diluting protocol for ethylene glycol (EG) was developed and verified. Osmotically inactive volumes (V(b)) of GV and MII oocytes were calculated to be 16.1% and 26.1%. The membrane permeability of the oocytes to water (L(p)) in the presence of EG were between 0.08-0.18 and 0.14-0.28 microm/min/atm, and the membrane permeability of the oocytes to solutes (Ps) were between 0.0011-0.0038 and 0.0029-0.0061 cm/min for GV and MII oocytes, respectively. The activation energies (E(a)) for L(p) and P(s) in the presence of EG were 3.68 and 6.84 kcal/mol for GV oocyte, while 3.62 and 0.83-9.08 kcal/mol for MII oocyte. The data indicated that L(p) and P(s) varied significantly between developmental stages and among temperatures evaluated. Based on these results, different protocols for EG adding and diluting from oocytes were developed and tested. The assessment of cleavage rate and embryonic development in vitro confirmed that the designed 4-step adding 2-step diluting protocol indicated a better outcome. The present study is helpful for better understanding of cryobiological properties and the design of cryopreservation protocols for bovine oocytes.
authors.affiliation: School of Agriculture, Food Science and Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland.
authors.forename: X
authors.initials: X
authors.lastname: Wang
authors.forename: A
authors.initials: A
authors.lastname: Al Naib
authors.forename: Da-Wen
authors.initials: DW
authors.lastname: Sun
authors.forename: P
authors.initials: P
authors.lastname: Lonergan
mesh_terms: D000818:Animals; D002417:Cattle; D002463:Cell Membrane Permeability / Q000187:drug effects*; D015925:Cryopreservation / Q000379:methods* / Q000662:veterinary; D003451:Cryoprotective Agents / Q000494:pharmacology*; D019855:Ethylene Glycol / Q000494:pharmacology; D005260:Female; D009865:Oocytes / Q000187:drug effects* / Q000378:metabolism; D009995:Osmosis
chemical_list: D003451:Cryoprotective Agents; D019855:Ethylene Glycol