Levels of estradiol and progesterone in the cerebrospinal fluid of rhesus monkey during the menstrual cycle.

Serum and cerebrospinal fluid levels of estradiol and progesterone were measured by radioimmunoassay on various days of the menstrual cycle. A correlation coefficient of 0.98 was obtained between serum and cerebrospinal fluid levels of progesterone. No such correlation was found for estradiol (correlation coefficient 0.08).