Abstract
Oxytocic activity of the ovarian follicles was investigated by measuring uterine contraction in vitro. Chickens were anesthetized and the three largest preovulatory and the most recently ruptured (R1) follicles were removed from the ovary immediately after oviposition or before ovulation. Each follicle was homogenized, centrifuged and the supernatant was added to the uterine strip in the chamber. Addition of the supernatant of the third largest follicle was ineffective but the first largest (F1) and the R1 follicles increased uterine contractions 2 fold. This stimulatory effect was not induced by the R1 follicle of hens injected with indomethacin 4h before removal of the follicle. There was only 50% increase in uterine contractions by the F1 follicle of the chicken pretreated with indomethacin. The supernatant of the thecal tissue of the F1 follicle elicited uterine response to the same degree as the whole tissue of the follicle whereas that of the granulosa tissue caused no increase. These results indicate that the R1 follicle may have prostaglandins (PGs) and that the F1 follicle may have some uterine contraction-inducing factor in addition to PGs. Uterine contraction-inducing factor of the F1 follicle may be predominantly present within the thecal tissue.NISHIO et al.: UC-IF of chicken ovarian follicles 125
We thank Mr. David Zadworny (University of Guelph, Canada) for reviewing this manuscript. This study was partly supported by Grants-in-Aid (Nos. 56480060 and 57560263) from the Ministry of Education, Science and Culture of Japan.
