Analysis of Oocyte Quality and Fertilization

Abstract

Before discussing quality evaluation of human oocytes, it is appropriate to comment on oocyte recovery techniques. In general, when searching for oocytes in follicular fluid, the operator must be aware of the possible detrimental effects of oocyte exposure to room air, undesirable pH in CO₂-bicarbonate buffered solutions, temperature changes, and to ambient lighting. While it is difficult to quantitate adverse effects of these parameters when carefully controlled, it is well established that extremes of pH, temperature and light exposure are detrimental to mammalian embryos. Several options are available for controlling in vitro conditions including the use of buffers that are stable in room air such as phosphate or Hepes, working with an oil overlay and the use of heated stages or enclosed temperature controlled environments under reduced lighting conditions. Regardless of the procedures employed, a skilled, experienced operator should make every effort to minimize the exposure of eggs in follicular fluid or in culture medium to adverse environmental conditions.