It has been considered the use of a mini-microscope, or saliva microscope, made up of a small cylindrical body or eyepiece where we note an optical part with an opposite small slide where a sample of saliva is placed. As soon as the sample of saliva has dried, the small eyepiece body is put into a cylindrical container that leads down to a lighting system. By focusing the lens, a fern-like characteristic crystallization is pointed out, in a very near correlation with the ovulation period (Figure 3). Out of the fertile days there are no fern-like crystallization structures seen, as pictures named "Figure 1" (during the non-fertile period) and "Figure 2" (during the intermediate period) indicate.

We have taken into consideration 328 women between 15 and 50 years old, not using OCP who were placed under our observation at the out-patients' departments of the Institute of Obstetrics and Gynecology of the University "La Sapienza" in Rome. No selective principle has been adopted. We have only invited the patient to leave a sample of saliva on the slide of the mini-microscope, and afterwards age, day of the cycle in which the patient was and length of her cycle were noted. 48 women, whose sample of saliva gave the fern-like characteristically stratification were invited to undergo an ultrasonography with transvaginal sound for the control of the ovarium and of the presence or not of the pertinent follicle. 20 women accepted our request, 28 women kindly refused.