The present authors examined follicular development, the LH surge, and luteal gonadotropin levels in spontaneous menstrual cycles of normal women. They addressed specific questions regarding the control of corpus luteum function by extrinsic factors: 1) Does the degree offollicular development determine the quantity of progesterone secreted after ovulation? 2) Does the magnitude of the LH surge determine the quantity of progesterone secreted after ovulation? 3) is there a relation between LH and progesterone secretion in the luteal phase? ls progesterone secretion pulsatile and coupled with LH secretion? Fourteen women, aged 23 to 33 years, participated in the study.

One complete menstrual cycle was studied for each subject. The average cycle length was 29.3: t: 0.8 days. When the integrated estradiol level in the late follicular phase for each subject was compared with the mean follicular diameter on the day before ovulation, there was a significant correlation (r= 0.65, P< 0.05). This finding indicates that there is a positive correlation between follicle size and estradiol secretion. When both of these parameters of follicular development were compared with integrated progesterone levels in the luteal phase, there was nO COrrelation. Furthermore, there was nO COrrelation be-tween the area under the LH surge and integrated luteal progesterone secretion. These data indicate that the de-gree of follicular development and the height of the LH surge are not quantitative determinants of corpus luteum function in normal menstrual cycles. In the midluteal and late-luteal phases, the LH pulse frequency exhibited a tendency (not significant) to be slower, with an increase in LH pulse amplitude in the midluteal phase, as compared with the late luteal phase. There was a significant positive correlation (P< 0.05) in the midluteal phase between the duration of the interpulse interval and the amplitude of the ensuing LH pulse. This relationship was not present in the late luteal phase. The late luteal pattern of LH secretion appeared to continue