Effect of Ca2+/Mg2+-free culture condition on spontaneous first cleavage of rat oocytes

• Published in: The Journal of reproduction and development 2002-06, Vol.48 (3), p.243-248
• Main Authors: Takeuchi, A. (Shinshu Univ., Ueda, Nagano (Japan). Faculty of Textile Science), Kato, M, Ito, K, Kimura, K, Hanada, A, Hirabayashi, M, Hochi, S
• Format: Article
• Language: English
• Subjects: AGING; CATIONS; CULTURE TECHNIQUES; EGG SEGMENTATION; IN VITRO CULTURE; OVA; RATS; STRONTIUM
• ISSN: 0916-8818; 1348-4400
• DOI: 10.1262/jrd.48.243

The aim of this study was to investigate the effect of Ca**2+- and Mg**2+ -free culture conditions on induction of spontaneous first cleavage in rat oocytes. Oocytes recovered from superovulated Wistar females 17 h after hCG injection were exposed for 1.5 h to Ca**2+/Mg**2+-free, Ca**2+-free, Mg**2+-free, or control mKRB medium supplemented with 5 micro g/ml cytochalasin-B (CB). The oocytes were then cultured for 4.5 h in control medium containing CB and for 28 h in CB-free control medium. The oocytes exposed to the Ca**2+/Mg**2+-free medium (23%) cleaved better than those exposed to Ca**2+-free (8%), Mg**2+-free (0%), or control (0%) media. The cleavage rates of oocytes recovered 12, 17 and 22 h after hCG injection and exposed to the Ca**2+/Mg**2+-free medium were 4, 17 and 22“, respectively. The efficiency of oocyte activation in 1.25 mMSr**2+ treatment for 6 h was not influenced by the culture background of bivalent cations (cleavage rates: both 49% in Ca**2+/Mg**2+-free and Ca**2+-medium). These results indicate that Ca**2+-/Mg**2+-free culture condition induced the spontaneous first cleavage of rat oocytes in an age dependent manner, but had no additional effect on Sr**2+-induced oocyte activation.