A prospective analysis of endometrial cycle changes by ultrasound in the female cynomolgus monkey

Endometrial cycle changes in adule female cynomolgus monkeys with normal ovulatory cycles were examined prospectively by real-time ultrasound. Endometrial thickness, as measured by ultrasound, was correlated with cycle day and serum estradiol (E2) and progesterone (P4) levels. We conclude that ultrasound is a reliable method of diagnosis of endometrial cycle stage.