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1 February 2001 Ethylenediamine-N,N,N′,N′-Tetraacetic Acid Induces Parthenogenetic Activation of Porcine Oocytes at the Germinal Vesicle Stage, Leading to Formation of Blastocysts
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Abstract

The present study showed that treatment with a cell membrane-impermeable metal ion chelator, EDTA, of porcine oocytes at the germinal vesicle (GV) stage collected from follicles 2–6 mm in diameter induced artificial activation followed by formation of a pronucleus (PN). When the oocytes were cultured for 48 h in medium containing 0.1 to 2 mM EDTA disodium salt (Na-EDTA), they were activated to form PN, and the maximum PN formation rate (63%, n = 68) was achieved in oocytes cultured with 1 mM Na-EDTA. More than 90% of oocytes activated by 1 mM Na-EDTA treatment formed 1 PN without emission of the first and the second polar bodies (PB). This result suggests that EDTA at 1 mM may force the maturing (meiosis I) oocytes to form a PN without chromosome segregation. When oocytes at the GV stage that had been cultured with 1 mM Na-EDTA for 48 h were further cultured in 0.4% BSA-containing NCSU23 medium for 144 h, blastocysts that appeared to be morphologically normal were formed at the rate of 10%, whereas no blastocysts were formed from oocytes that had not been cultured with Na-EDTA. Next we examined the effects of Ca2 , Zn2 , Fe3 , or Cu2 -saturated EDTA (Ca-EDTA, Zn-EDTA, Fe-EDTA, and Cu-EDTA, respectively), and a Ca2 -specific chelator, EGTA, at a concentration of 1 mM. The Ca-EDTA, Fe-EDTA, and Cu-EDTA, but not Zn-EDTA or EGTA, had the ability to activate the oocytes. From these results, it is suggested that extracellular chelation of Zn2 with EDTA of maturing (meiosis I) porcine oocytes results in parthenogenetic activation of the oocytes, which induces PN formation followed by development to blastocysts.

Tohru Azuma, Shuntaro Ikeda, Takuya Kondo, Hiroshi Imai, and Masayasu Yamada "Ethylenediamine-N,N,N′,N′-Tetraacetic Acid Induces Parthenogenetic Activation of Porcine Oocytes at the Germinal Vesicle Stage, Leading to Formation of Blastocysts," Biology of Reproduction 64(2), 647-653, (1 February 2001). https://doi.org/10.1095/biolreprod64.2.647
Received: 31 July 2000; Accepted: 1 October 2000; Published: 1 February 2001
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