Zygote

Research Article

Prediction of maturational competence of feline oocytes using supravital staining of cumulus cells by propidium iodide

Kenzo Uchikuraa2a3, Masashi Naganoa1 c1 and Mitsugu Hishinumaa2

a1 Laboratory of Theriogenology, Department of Veterinary Clinical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo 060–0818, Japan.

a2 Department of Theriogenology, School of Veterinary Medicine, Faculty of Agriculture, Tottori University, 4–101 Koyama-Minami, Tottori 680–8553, Japan.

a3 The United Graduate School of Veterinary Science, Yamaguchi University, 1677–1 Yoshida, Yamaguchi 753–8515, Japan; 1 Laboratory of Theriogenology, Department of Veterinary Clinical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo 060–0818, Japan.

Summary

We examined the relationship between integrity of cumulus cells and nuclear maturation rate after in vitro culture to determine a non-invasive prediction of the maturational competence of feline oocytes. Feline cumulus–oocyte complexes (COCs) were collected from either small (400–800 μm) or large (≥800 μm) follicles. Immediately after collection, cumulus cells were evaluated morphologically (thickness of cumulus cell layers) and stained with propidium iodide (PI), which penetrates only non-viable cells. Cumulus cells without PI staining were judged as having good membrane integrity. After evaluation, COCs were cultured for 30 h and their nuclear maturation rate was determined. The nuclear maturation rate of oocytes derived from large follicles (89.8%) was higher (p < 0.05) than that from small follicles (60.8%). There was no difference in the maturation rate of oocytes from follicles with the same size regardless of cumulus morphology. In contrast, oocytes that had cumulus cells with good membrane integrity showed a higher maturation rate (93.8%) than oocytes with poor cumulus integrity (76.9%) in large follicles (p < 0.05). We conclude that evaluation of membrane integrity of cumulus cells by propidium iodide staining can be used to predict the maturational competence of oocytes.

(Received December 03 2010)

(Accepted March 02 2011)

(Online publication May 18 2011)

Keywords:

  • Cat;
  • Follicle;
  • IVM;
  • Membrane integrity;
  • Propidium iodide

Correspondence:

c1 All correspondence to: Masashi Nagano. Laboratory of Theriogenology, Department of Veterinary Clinical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo 060–0818, Japan. Tel:/Fax: +81 11 706 5232. e-mail: mnaga@vetmed.hokudai.ac.jp

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