The effects of amino acids, cumulus cells, and bovine serum albumin on in vitro fertilization and first cleavage of hamster eggs.

Abstract

Three factors were studied for their effects on the first cleavage division of in vitro fertilized hamster eggs. Eggs from superovulated females were inseminated with precapacitated epididymal hamster sperm in medium containing either fatty acid-free (FAF) or fraction V (V) bovine serum albumin (BSA), in the presence or absence of cumulus cells. After incubation for 3 to 4 h with sperm, eggs were transferred to culture medium containing FAF- or V-BSA, with or without amino acids (glutamine, isoleucine, methionine, and phenylalanine), and the percentages of eggs cleaving to two cells were recorded after a further 20 h of incubation. Fatty acid-free BSA was found to support a significantly higher percentage of eggs cleaving than V-BSA and was used in all further experiments. The presence of cumulus cells during fertilization was found to have a beneficial effect on cleavage when no amino acids were added to the culture medium, but when amino acids were included, eggs fertilized with or without cumulus present cleaved equally well. These results represent another step toward defining the optimal environmental conditions for obtaining the first cleavage division of hamster eggs in vitro.