IN-VITRO STUDY OF THE CONTRACTILITY OF THE WALL OF THE PREOVULATORY FOLLICLE IN THE JAPANESE-QUAIL

In the present study, we examined in vitro the potassium-induced contr actions of isolated parts of the wall of the quail preovulatory follic le through use of an electromagnetic force-length transducer system. W e studied longitudinal and transverse strips of the whole wall, of the theca, and of the outer layer (tunica albuginea and surface epitheliu m). It was observed that force development and shortening of strips of the whole wall and those of the theca are similar. Statistical analys is of maximal isometric force, peak shortening length, and percentage of reduction of follicular volume showed that the orientation of strip s is without importance. Results from different orientations were pool ed, and the different layers were compared statistically. The general result of this analysis was that the contractile activity of the outer layer was significantly lower than the performance of either the whol e wall or the theca. We concluded that contraction of the follicular w all is mainly dependent on the contractile activity of the theca exter na. This contractile system is comparable to that of mammals. We sugge st that the main function of the theca externa during ovulation is to maintain a constant intrafollicular pressure.