Fig. 4

Heat-treated transgenic embryos developed into infertile male adults.

(A) No difference in appearance or overall size was observed between adult transgenic fish that developed from heat treated embryos and wild-type male. (B) No significant difference in body-weight of 3.5-month-old fish (n = 16 by random sampling) among heat-treat transgenic males, untreated transgenic males and wild-type males, and between the transgenic females and wild-type females. Data shared the same letter (A or B) are not significantly different from each other. Examination of gonadal tissue revealed that (C) A well-developed testis, C1, of untreated male transgenic fish. (D) A well-developed ovary, D1, of untreated female transgenic fish. (E) The gonads of heat-treated transgenic fish developed into a thin filament-like tissue, E1, surrounded by adipocytes. Photomicrograph showing (F) active spermatogenesis of the testis of untreated male transgenic fish, (G) a well-developed ovary with oocytes at different developmental stages of untreated female transgenic fish. (H) The gonad of heat-treated transgenic fish appears to be under-developed and surrounded with large amount of adipocytes without advanced gonadal structure or germ cells. WT: wild type; TG: transgenic; HT: heat treated. Scale bar: 1 cm for A, C–E and 50 μm for F–H. S: spermatozoa.