抄録
ETO and IMAMICHI (1955) reported that ova had been observed in the oviduct inserted betweentwofold glass slides by the dissecting microscope at 20 hours after a single subcutaneous injection of HCG in a diestrous adult female rat. This finding was significant for the bioassay of gonadotrophin.
The authors showed that the sensitivity induced ovulation by HCG was elevated in the case of intravenous injection, as a result of comparison between s.c., i.p., and i.v. injection. Moreover, ovulation was induced 10 hours after injection of HCG (more than 2IU) and ova were observed in the oviduct 12 hours after injection.
This report is concerned with the interval between the induced ovulation by intravenous injectionof HCG (injection being done at 4-5 PM on the day of diestrous stage) and spontaneous ovulation thereafter and with the fate of ova ovulated by HCG injection in adult rats.
The following results were obtained.
1) The interval between the induced ovulation and the first spontaneous ovulation thereafter (72hours) was 3 days, which was shorter than 4 days (96 hours) that is the interval between two spontaneous ovulations in the normal oestous cycle.
2) In the ovulation induced by such an amount of HCG as sufficient to induce ovulation, no tubal ova were observed during 14 and 24 hours before the first spontaneous ovulation after the induced ovulation. In the normal oestrous cycle, no the ova by spontaneous ovulation was observed during 24 and 34 hours before the next ovulation.
Namely, in normal-cyclic rats, ova remained in the oviduct for about 72 hours after spontaneous ovulation, and in the case of induced ovulation ova remained in the oviduct about 58 hours after the induced ovulation by HCG injection.
3) In the first spontaneons ovulation after the induced ovulation by HCG, an ovulation-blockade by pentobarbital (nembutal) anesthesia was seen when the animal was anesthetized during a period from noon to 2 PM on the day before the ovulation, but it was not seen when the animal was anesthetized during a period from 4 to 6 PM on the day before the ovulation.
4) In the first oestrus after the induced ovulation by HCG, the accumulation of uterine fluid was smaller in amount than in the normal proestrous stage.
5) When examined by the vaginal smear method, the animal with the estrous cycle of induced ovulation by HCG showed stages I, IV, II, and III, but the animal in which no ovulation had occurred showed stages I, III, IV, and V in the same manner as the animal with the normal oestrous cycle.
