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Effect of 1,2-propanediol and dimethylsulphoxide on the meiotic spindle of the mouse oocyte.

At ovulation, the mouse oocyte is arrested at metaphase of the second meiotic division. Since microtubules are thermo-and chemosensitive structures, the effects of 1.5 M dimethylsulphoxide and 1.5 M 1,2-propanediol were studied at room temperature on the morphology of the meiotic spindle. Oocytes incubated at 37 degrees C or at room temperature served to estimate the effect of temperature in the experiment. The meiotic spindle was visualized by immunogold-silver staining of microtubules. In the control group at 37 degrees C, 88% of oocytes had normal spindles. After incubation at room temperature for the same time, 89% of oocytes showed abnormal spindles. In the oocytes exposed to dimethyl-sulphoxide or 1,2-propanediol at room temperature a protective effect on spindle morphology could be recognized. Subsequent incubation at 37 degrees C resulted in partial restoration of the observed abnormalities after cooling to room temperature and after exposure to dimethylsulphoxide. Incubation at 37 degrees C after exposure to 1,2-propanediol at room temperature induced spindle absence in the majority of oocytes. Although this latter condition allowed fertilization without increased incidence of ploidy abnormalities, a role for 1,2-propanediol as an activating agent is hypothesized.