title: Gonadal structure of the serial-sex changing gobiid fish Trimma okinawae.
abstract: In order to obtain basic information about the role played by endogenous sex hormones in bringing about sex changes in the serial-sex changing gobiid fish Trimma okinawae, the gonadal structure of male and female phases were observed histologically. Steroid-producing cells (SPC; Leydig cells in a testis) were observed ultrastructurally in the ovaries and testes of both female-phase and male-phase fish. In addition, gonadal expression of P450 cholesterol side-chain-cleavage (scc) was examined immunohistochemically. Gonads of fish in female and male phases were observed to have both ovaries and testes simultaneously. Female-phase fish had matured with many developed vitellogenic oocytes, while male-phase individuals had immature ovaries with many numbers of previtellogenic oocytes at the perinucleolus stage. Testes of fish in different sexual phases had active spermatogenic germ cells. Organellae of SPC in the ovaries of female-phase fish had active structures of steroid production. In contrast, SPC in the ovaries of male-phase fish did not show active structures of steroid production. Immunopositive reactions against the scc antibody in the ovaries of female-phase fish were very strong, but immunoreactions in the ovaries of male-phase fish were very weak. In the testis, moderate immunopositive signals were obtained from dual-phase male/females.
authors.affiliation: Sesoko Station, Tropical Biosphere Research Center, University of the Ryukyus, 3422 Sesoko, Motobu-cho, Okinawa 905-0227, Japan.
authors.forename: Yasuhisa
authors.initials: Y
authors.lastname: Kobayashi
authors.forename: Tomoki
authors.initials: T
authors.lastname: Sunobe
authors.forename: Tohru
authors.initials: T
authors.lastname: Kobayashi
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Nagahama
authors.forename: Masaru
authors.initials: M
authors.lastname: Nakamura
mesh_terms: D000818:Animals; D002786:Cholesterol Side-Chain Cleavage Enzyme / Q000378:metabolism; D005260:Female; D006066:Gonads / Q000033:anatomy & histology* / Q000378:metabolism; D057850:Hermaphroditic Organisms; D006652:Histological Techniques; D007150:Immunohistochemistry; D007985:Leydig Cells / Q000648:ultrastructure*; D008297:Male; D008854:Microscopy, Electron; D010473:Perciformes / Q000033:anatomy & histology*; D019849:Sex Determination Processes
chemical_list: D002786:Cholesterol Side-Chain Cleavage Enzyme