English to Russian Medical Biology (-tech,-chem,micro-) in vitro fertilization

Oocytes (pHi 7.4) are sensitive to extracellular pH fluctuations
cytoskeletal and metabolic changes (Dale et al., 1998; Swain and Pool, 2009)
Constant pH of 7.3 in media
HEPES-buffered media (CO2 independent)
Bicarbonate buffered media (CO2 dependent)



The intracellular pH (pHi) of oocytes is around 7.4 during maturation and fertilization. Following alkaline shock oocytes are capable of regulating their pHi, but, they are extremely sensitive to acid shock (Dale, 1998; Swain and Pool, 2009). In order to avoid pH fluctuations of the external pH and also indirectly the intracellular pH, oocytes are collected in HEPES (4-(2-hydroxyethyl)-1-piperazine-ethane sulfonic acid) buffered or bicarbonate buffered media at pH 7.3. HEPES buffered media do not require a CO2 atmosphere, whereas bicarbonate buffered media do and therefore, have to be ***equilibrated beforehand in an incubator***. Care should be taken to keep the time outside the incubator for bicarbonate buffered media as short as possible.