[Pattern of gonadotropins and ovarian steroids during the menstrual cycle in adolescence (author's transl)].

Serial determinations of FSH, LH, estradiol-17 beta and progesterone in plasma and of total gonadotropins, total estrogens and pregnanediol in urine were performed in 10 adolescent girls between 15 and 19 years of age. Two types of menstrual cycles could be distinguished. The first type is characterized by a nearly normal pattern of FSH, while a preovulatory rise of estradiol-17 beta and an LH-peak is still missing. Only few days prior to menstrual bleeding a small rise of estradiol and progesterone in plasma as well as of estrogens and pregnanediol in urine can be seen, being equivalent to a short luteinization of the follicle without ovulation taking place. The second type already shows all criteria of a regular ovulatory cycle. However the plasma level of LH, estradiol and progesterone and the excretion of estrogens and pregnanediol are still below the average values of control cycles of adult women. On the basis of the hormonal pattern and a shortened luteal phase, a relative insufficiency of this type of cycles is still evident. These studies demonstrate, that the cyclic ovarian function postmenarchial develops gradually and that the onset of ovulation is a marked step in this development. This process of maturition, which is due to the gradual development of the positive feedback of estrogens on the release of LH by the pituitary gland, allows to distinguish in adolescence between cycles before and after maturition of the feed-back mechanism in the ANS.