Effect of aspiration vacuum on the developmental competence of immature human oocytes retrieved using a 20-gauge needle.

In-vitro maturation (IVM) of immature oocytes has been proposed as a potential alternative to conventional IVF treatment following ovarian stimulation. However, the effects of the oocyte retrieval conditions on subsequent development have not been well understood. This study assessed the effects of different aspiration vacuums during oocyte retrieval on the developmental competence of immature oocytes following IVM, IVF and embryo transfer, retrospectively. Immature oocytes were aspirated with 20-gauge needles with a vacuum of 180 or 300 mmHg. Immature oocytes were cultured in IVM medium for 26 h. All mature oocytes were inseminated by intracytoplasmic sperm injection (ICSI). Embryo transfer was carried out 2 or 3 days after ICSI. The percentage of cumulus-cell enclosed oocytes and of transferable embryos per retrieved oocytes in 180 mmHg (69.7% and 23.8%, respectively) were significantly higher (P < 0.01) than those in 300 mmHg (46.2% and 12.8%, respectively). The ongoing pregnancy rate per retrieval cycle in 180 mmHg (30%) was higher (P < 0.01) than that in 300 mmHg (4.3%). The data indicate that lower pressure of vacuum aspiration with a 20-gauge needle improves the developmental competence of immature oocytes following IVM, IVF and embryo transfer.

Amino acid-permeable anion channels in early mouse embryos and their possible effects on cleavage.

Effects of several Cl(-) channel blockers on ionic currents in mouse embryos were studied using whole-cell patch-clamp and microelectrode methods. Microelectrode measurements showed that the resting membrane potential of early embryonic cells (1-cell stage) was -23 mV and that reduction of extracellular Cl(-) concentration depolarized the membrane, suggesting that Cl(-) conductance is a major contributor for establishing the resting membrane potential. Membrane currents recorded by whole-cell voltage clamp showed outward rectification and confirmed that a major component of these embryonic currents are carried by Cl(-) ions. A Cl(-) channel blocker, 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS), suppressed the outward rectifier current in a voltage- and concentration-dependent manner. Other Cl(-) channel blockers (5-nitro-2-[3-phenylpropyl-amino] benzoic acid and 2-[3-(trifluoromethyl)-anilino] nicotinic acid [niflumic acid]) similarly inhibited this current. Simultaneous application of niflumic acid with DIDS further suppressed the outward rectifier current. Under high osmotic condition, niflumic acid, but not DIDS, inhibited the Cl(-)current, suggesting the presence of two types of Cl(-) channels: a DIDS-sensitive (swelling-activated) channel, and a DIDS-insensitive (niflumic acid-sensitive) Cl(-) channel. Anion permeability of the DIDS-insensitive Cl(-) current differed from that of the compound Cl(-) current: Rank order of anion permeability of the DIDS-sensitive Cl(-) channels was I(-) = Br(-) > Cl(-) > gluconate(-), whereas that of the DIDS-insensitive Cl(-) channel was I(-) = Br(-) > Cl(-) >> gluconate(-). These results indicate that early mouse embryos have a Cl(-) channel that is highly permeable to amino acids, which may regulate intracellular amino acid concentration.