Relationship between plasminogen activator activity in granulosa and follicular transformation to the rapid growth phase of small follicles
2009
Takeishi, M.(Laboratory of Nippon Formula Feed Mfg. Co., Ltd., Tochigi (Japan)) | Azumi, M. | Nishida, S. | Yamamura, N. | Goto, H. | Shibui, H. | Doi, O. | Kamiyoshi, M.
In domestic fowl, estradiol-17beta (E2) is reported in relation to the follicular transformation to the rapid growth phase of small follicles. However, the participation of the plasminogen activator (PA) in granulosa, which is known to be involved in cell proliferation and extra-cellular matrix remodeling, is not sufficiently clear. To confirm its participation, follicles from the largest follicle (F1) to the ninth largest follicle (F9) were collected at 18 hours before ovulation of the F1 and weighed. In the follicles, the activity of PA in granulosa was measured using plasminogen extracted from rooster's plasma and chromogenic substrate. DNA content of granulosa was determined by the diphenylamine method. Also, E2 in theca was determined by radioimmunoassay. Morphological investigation of ovarian follicles was implemented by the usual method. Follicular weight increased significantly from F6 to F5, and thereafter in a straight manner until F1. The material transfer rate of follicles increased significantly from F6 to F5, and the peak was from F5 to F4, and then decreased according to the growth of follicles. Both the PA activity of granulosa and the E2 concentration of theca increased significantly from F8 to F7, showed a peak in F7 and decreased according to the growth of follicles. The granulosa layer changed from multilayer into monolayer in the developmental stage from F7 to F5. DNA content of granulosa increased from F9 to F5, and thereafter remained constant. In the present experiment, follicular transformation of the rapid growth phase of small follicles was found to occur in F6, and both E2 and PA activity increased before the follicular transformation. This suggests that not only E2 of theca but also PA activity of granulosa participate in the transformation to the rapid growth phase of small follicles.
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