Fig. 3

Expression pattern of amh during zebrafish gonad development. In situ hybridization was performed on sections of (A,B) undifferentiated gonads; (C,E,G,I) male gonads; (D,F,H,J) female gonads. (A) The earliest amh expression we observed was weakly detected transcript in 17 days post-fertilization (dpf) larvae. (B) Amh expression became more intense in the still undifferentiated gonads of 21 dpf larvae. (C,D) In 31 dpf juveniles, gonads were already differentiated into testes and ovaries. At this time, amh expression was detected only in testes (C) and was not detected in ovaries (D). (E,F) In 38 dpf larvae, as gonad development proceeded, amh maintained the same sexually dimorphic expression pattern. (G–J) In contrast to larval and juvenile stages, adults showed amh expression in both testes and ovaries. In males, amh expression was detected only in presumptive Sertoli cells (G). A higher magnification of a region expressing amh (dashed box) is shown in (I). In adult ovaries, amh expression differed among oocytes of different stages (IB, II, III) (H). Expression of amh was mostly detected in the monolayer of granulosa cells (gc) of Stage II oocytes (red arrowhead in H), but no expression of amh was detected in Theca cells (tc). Only reduced number of amh expressing cells could be detected in late stage IB oocytes (orange arrowhead) or early stage III oocytes (purple arrowhead), and no expression was detected in late stage III oocytes (green arrowhead). A higher magnification of a region expressing amh (dashed box) is shown in (J). Scale bars are indicated in each panel. ca, cortical alveoli; gc, granulosa cells; gv, germinal vesicle; o, ooplasm; tc, theca cells; y, yolk. Colored arrowheads label different stages of oocytes: orange, late stage IB; red, stage II; purple, early stage III; green, late stage III.