The importance of the presence of metabolizable sugars in a medium for in vitro fertilization of hamster eggs with postovulatory oviduct contents

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Abstract
Hamster eggs with postovulatory oviduct contents were added to a simple defined medium, without serum albumin, but supplemented with different combinations of energy sources. They were then inseminated by epididymal spermatozoa. In a medium containing D‐glucose but without pyruvate and/or lactate, high proportions of acrosome‐reacted spermatozoa (78–94%) and eggs undergoing fertilization (89–96%) were obtained 9–9.5h after insemination. With only pyruvate or lactate as substrates, or with both pyruvate and lactate, acrosome reactions occurred in only 2–4% of the sperm. When D‐glucose ranging in concentration from 2.78 to 8.34 mM was added, a high proportion (82–95%) of the eggs inseminated were found to be fertilized. Substituting D‐galactose, L‐glucose, L‐fucose, D‐lactose, or D‐saccharose for D‐glucose resulted in very low numbers of acrosome‐reacted sperm (0–12%) and fertilized eggs (0–7%). However, in the presence of metabolizable sugars, such as D‐mannose or D‐fructose, the acrosome reaction was seen in 78–85% of the sperm examined and 87–95% of the eggs tested were fertilized.