The luteal corpuscles can be seen in the abdominal ultrasound examination around 7-8 days after ovulation, after a woman expels her eggs to form the luteal corpuscles, she can secrete progesterone, the egg and sperm will combine to form a fertilized egg, under the action of progesterone, early pregnancy reaction symptoms will gradually appear. To determine when to ovulate, you can do follicular monitoring of ovulation through ultrasound. You can start ultrasound monitoring 2-3 days before the middle of your period, and ultrasound exams will be done every other day. If there are mature follicles, it means that you are about to ovulate, and the probability of pregnancy is higher when you have intercourse at this time.