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Oocyte activation and parthenogenetic development of bovine oocytes following intracytoplasmic sperm injection

Published online by Cambridge University Press:  01 August 1999

Xihe Li
Affiliation:
Maebashi Institute of Animal Science, Livestock Improvement Association of Japan, Inc., 316 Kanamura-machi, Maebashi 371-0121, Japan. University of Cambridge, Department of Clinical Veterinary Medicine Equine Fertility Unit, Mertoun Paddocks, Woodditton Road, Newmarket, Suffolk CB8 9BH, UK.
Koh-ichi Hamano
Affiliation:
Maebashi Institute of Animal Science, Livestock Improvement Association of Japan, Inc., 316 Kanamura-machi, Maebashi 371-0121, Japan. Research Farm, Faculty of Agriculture, Shinshu University, 8304 Minamiminowa, Nagano 399-4598, Japan.
Xiao-qiao Qian
Affiliation:
Maebashi Institute of Animal Science, Livestock Improvement Association of Japan, Inc., 316 Kanamura-machi, Maebashi 371-0121, Japan.
Katsutoshi Funauchi
Affiliation:
Maebashi Institute of Animal Science, Livestock Improvement Association of Japan, Inc., 316 Kanamura-machi, Maebashi 371-0121, Japan.
Makoto Furudate
Affiliation:
Maebashi Institute of Animal Science, Livestock Improvement Association of Japan, Inc., 316 Kanamura-machi, Maebashi 371-0121, Japan.
Yoshiaki Minato
Affiliation:
Maebashi Institute of Animal Science, Livestock Improvement Association of Japan, Inc., 316 Kanamura-machi, Maebashi 371-0121, Japan.

Abstract

Development of bovine oocytes after intracytoplasmic sperm injection (ICSI) was investigated. Oocytes were matured for 24–26 h in vitro and injected with isolated sperm heads. When treated with 7% ethanol (v/v) for 5 min, 71.7% of ICSI oocytes were activated as shown by the resumption of meiosis and the formation of female pronuclei. However, 41.5% of injected sperm heads remained condensed at 18–20 h after injection into the ooplasm. The incidence of decondensing sperm and that of male pronuclei at this stage were 15.1% and 26.4%, respectively. A total of 55.5% of oocytes reached the 2-cell stage following sperm head injection and 54.7% after sham-ICSI; these percentages were not significantly different from those following in vitro fertilisation (IVF) (73.1%). The percentage of 2-cell embryos reaching the 8-cell stage following ICSI was 37.5%, and 27.6% after sham-ICSI, which were significantly lower (p < 0.01) than the equivalent percentage following IVF (62.4%). The percentages of parthenogenetic embryos reaching the 2-cell, 4-cell and 8-cell stages following ICSI were 56.4%, 48.9% and 30.0%, respectively. These results indicate that the low rate of normal embryonic development of bovine oocytes following ICSI is largely due to the parthenogenetic activation of the oocytes.

Type
Research Article
Copyright
1999 Cambridge University Press

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