[Hemodynamical and histological studies on ovarian blood flow during ovulation (author's transl)]

The author, in an attempt to investigate the mechanism of ovulation, conducted studies on ovarian blood flow hemodynamically and ovarian vessels histologically during ovulation induced by FSH and LH in rabbits. Continuous measurement of ovarian blood flow was facilitated by the crossed-thermocouple inserted into the unilateral ovary relatively close to its cortex. Histological changes of the ovarian blood vessels were observed every two hours and 13 h after LH administration. (1) The ovarian blood flow showed a rapid increase as 116.6 +/- 4.3% (M +/- S.E) at 15 min, 122.1 +/- 5.1% at 30 min following LH administration and maintained its high level percentage during the subsequent 2 h to 4 h, showing the peak with 156.2 +/- 9.1%. The ovarian blood flow showed a gradual decrease after 4 h. (2) A dilatation was observed in the perifollicular and stromal vessels from 2 h. The vessels maintained a considerable dilatation during 4 h to 8 h and the most conspicuous vasodilatation was manifested, especially at the apical vessels, at 10 to 13 h just prior to ovulation. Although the wall of the apical vessels was remarkably thin at that time, the overswelled apical vessels remained until ovulation. The ovulation was not seen without the rupture of the apical perifollicular vessels. These hemodynamic and histological results suggest a congestion in ovarian blood vessels during the ovulatory period. Such blood congestion presumably plays a significant role in the mechanism leading to ovulation.