Fluidity of the phospholipid bilayer of the endometrium at the time of implantation of the blastocyst--a spin label study.

The endometrial phospholipid bilayer is shown to be in a highly fluid and polar state at the time of implantation in Mus musculus as evidenced from a spin label study using the stearic acid spin label, 5-doxyl stearate. The positive correlation observed between the superoxide anion radical levels and the fluidity and polarity state of the endometrial cells points towards the possibility of the mediation of this condition of unsaturation of fatty acids to be an act of the superoxide anion radical.