Precocious ovulation induced by @entity1 chorionic gonadotrophin in the immature female XXXX : comparison of follicle growth induced by treatment with @entity1 chorionic gonadotrophin and by electrical stimulation of the hypothalamus.

@entity35 @entity1 @entity1465
Precocious first ovulation, preceded by an endogenous preovulatory LH surge, could be predictably induced in immature female @entity35 by administering repeated injections of @entity1 chorionic gonadotrophin ( @entity1465 ). Administration of a dose of 0.05-0.075 i.u. @entity1465 , four times a day from day 28 to day 31 of age resulted in a highly constant ovulatory response: at 4.0 +/- 0.0 days after the start of treatment 7.7 +/- 0.3 (n = 15) ova were found. Use of a higher dose of @entity1465 (0.1 i.u.) resulted in lower numbers of ova (5.6 +/- 0.4, n = 7; P less than 0.005) whereas use of a lower dose of @entity1465 (0.025-0.038 i.u.) resulted in a less constant timing of the induced ovulation at 5.4 +/- 0.2 days after the start of treatment (n = 7; P less than 0.0005). In animals treated with the dose of 0.05-0.075 i.u. @entity1465 , a positive correlation was found between body weight at the start of treatment and the number of ova released (r = 0.75, n = 25; P less than 0.001). Ovarian follicle dynamics were studied on the various days of @entity1465 treatment (dose 0.05-0.075 i.u.) and compared with the follicle changes that take place after electrical stimulation of the hypothalamus, performed on day 28, a treatment known to result in first ovulation 4-5 days later. In both groups a decrease in the number of the smallest and the middle-sized antral follicles as compared with their respective controls was seen, whereas numbers of follicles in the largest, 'ovulatable' size classes gradually increased.(ABSTRACT TRUNCATED AT 250 WORDS)
