Ovarian follicle in mammals becomes to be a corpus luteum after ovulation or be atretic finally. In recent years, a lot of clinical interests have been gathered forward to the luteinized unruptured follicle (LUF) as another structure appeared in
folliculogenesis. The LUF that can be induced by indomethacin administration, must be very useful for a research for the mechanism of ovualtion, especially the follicular repture.
In contrast to the trend of previous other investigation focusing on the preovulatory processing, the present study was designed to examine changes of steroid concentration in serum and histological changes of ovarian tissue after the induction
of
luteinized unruptured follicle by indomethacin administration.
Immature rats were superovulated by injection of PMSG (10IU) followed 48 hr later injection of hCG (10IU), and were treated with 3mg of indomethacin at the same time of hCG injection. At 12 hr and every 24 hr until 96 hr after indomethacin
treatment,
serum and ovaries were collected. Ovaries were sectioned and examined histologically using hematoxylin-eosin staining method. Concentrations of steroids were measured by radioimmunoassays.
It was revealed that the concentration of progesterone was decreased markedly in comparison with that of control at 12 hr after indomethacin treatment (p<0.05), so it maintained lower level though the duration of the present experiment. Serum
level
of
estradiol was temporaly decreased only at 12 hr after inomethacin treatment (p<0.05), and was recovered soon up to the control level.
As a result of histological examination, luteinized follicle appeared firstly at 12 hr after indomethacin treatment. Thus luteinization of follicles proceeded progressively from at 24 hr after indomethacin treatment. It was observed that oocytes
were
left inside follicles and that granulosa cells were floatted into antrum. Floating oocytes separated from cumulus cells were also seen in antrum.
In concusion, it seems that indomethacin inhibits the synthesis of ovarian steroids at the early stage of preovulatory processing. The luteinization mechanism of LUF looks like to be similar o that of normal follicles, but it is considered that
indomethacin may affect the follicular atresia and oocyte degeneration.
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