Plasminogen activator production by the granulosa layer is stimulated by factor(s) produced by the theca layer and inhibited by the luteinizing hormone surge in the chicken.

The stages of follicular maturation of a preovulatory follicle in the hen can be divided into an extended proliferative phase (prior to LH surge) and a brief ovulatory phase (after LH surge). Previous studies suggest involvement of plasminogen activator (PA) in both the proliferative and ovulatory phases. The goals of the present study were 1) to determine whether PA production by granulosa and theca is dependent upon interaction of the two cell layers; 2) to investigate whether the structural difference of the stigma (site of follicular rupture) and nonstigma regions of the theca layer affect PA production; 3) to determine whether there is a change in the ability of the granulosa layer and stigma or nonstigma regions of the theca layer to produce PA as the follicle makes the transition from the proliferative to the ovulatory phase; and 4) to characterize the type(s) of PA produced by the hen follicle. Equal proportions of the granulosa layer (10-mm diameter) and stigma or nonstigma regions of the theca layer (10 mg) obtained from the F1 preovulatory follicle 8 h before ovulation (before LH surge) or 2 h before ovulation (after LH surge) were incubated alone or in combination for 24 h. PA was measured in tissue homogenates and medium by use of the chromogenic substrate S-2251. The granulosa layer or stigma or nonstigma regions of the theca layer incubated alone and obtained either 8 h or 2 h before ovulation had very low amounts of PA activity in the medium and tissue homogenates.(ABSTRACT TRUNCATED AT 250 WORDS)