Evidence <i>in vivo</i> for the two-cell hypothesis of oestrogen synthesis by the sheep Graafian follicle

Abstract

After autotransplantation of different cell types to the anterior chamber of the eye in the rat, Falck (1959) proposed that granulosa and theca interna cells complemented one another in the synthesis of oestrogen by the Graafian follicle. Although numerous experiments in vitro support this 'two cell' hypothesis (Ryan, Petro &amp; Kaiser, 1968; Makris &amp; Ryan, 1975), most evidence suggests that in vivo oestrogen is synthesized exclusively by the theca cells (YoungLai &amp; Short, 1970; Channing &amp; Coudert, 1976). However, the report that FSH stimulates specifically the aromatization of androgens to oestrogens by ovaries in organ culture (Moon, Dorrington &amp; Armstrong, 1975), as well as by granulosa cells in tissue culture (Dorrington, Moon &amp; Armstrong, 1975), led us to re-examine the biosynthesis of oestrogens by the Graafian follicle in vivo. If androgens leave the thecal cell before aromatization, it should be possible to make them unavailable for the synthesis of oestrogen by antiandrogen antiserum.