Fig. 7. Perturbing secretion induces male-to-female germ cell sex reversal in embryonic gonad cultures. (A-R) Urogenital ridges (11.5 dpc) were transiently treated with or without brefeldin A to block secretion, or were cultured continuously with retinoic acid or ketoconazole. Urogenital ridges were cultured for 4 days and analysed by histology (Haematoxylin and Eosin) to assess germ cell development, and immunostained for anti-Mullerian hormone (AMH, brown precipitate) to assess Sertoli cell development. Urogenital ridges were also cultured for 6 days and immunostained for synaptonemal complex protein 3 (Sycp3). Sycp3 labels the thread-like synaptonemal complex in meiotic oocytes, and is present as large aggregates in prospermatogonia. Examples of meiotic oocytes are labelled with arrowheads; examples of prospermatogonia are labelled with arrows. Scale bars: 10 µm.