Regulation of sexual succession in the protogynous black sea bass, Centropristis striatus (Osteichthyes: Serranidae)
Serum levels of 17 beta-hydroxy-4-androstene-3,11-dione (11-KT) and testosterone in the protogynous black sea bass, Centropristis striatus fluctuate annually, correlated with the breeding season. Although serum 11-KT levels in both males and females exhibit seasonality, serum estradiol-17 beta concentrations cycle annually only in the females. Throughout the year, serum estradiol levels in males (127 +/- 56 pg/ml, mean +/- SD) were significantly (P less than 0.05) less than levels in breeding (3,930 +/- 1,390 pg/ml), or nonbreeding females (261 +/- 62 pg/ml). In all female sea bass not undergoing sexual succession, histological examination of the ovary revealed only spermatogonia or ongoing spermatogenesis restricted to the posterior male lamellae; a duct system was nonexistent. In female fish undergoing sexual succession, ovarian tissue was always nonvitellogenic and regressing. Breeding females were not observed to undergo gender change. During sexual succession in the postspawning period, male tissue spread into neighboring female lamellae containing oocytes, gradually replacing them and other female tissue. A male duct system developed on the surface. At any time of year, black sea bass undergoing sexual succession had serum estradiol levels (79 +/- 19 pg/ml) which were significantly less (P less than 0.05) than concurrent female serum estradiol levels. A chi-square test demonstrated that serum estradiol levels in these intersex animals were not significantly different from those of males. The possibility is discussed that sexual succession results from inhibition of ovarian tissue response to steroidogenic gonadotropin.
Cochran
R C
RC
Department of Population Dynamics, Johns Hopkins University School of Hygiene and Public Health, Baltimore, Maryland 21205.
Grier
H J
HJ
D000375:Aging; D000818:Animals; D001492:Bass / Q000502:physiology*; D004958:Estradiol / Q000097:blood; D005260:Female; D057850:Hermaphroditic Organisms; D008297:Male; D009865:Oocytes / Q000166:cytology; D010053:Ovary / Q000166:cytology; D012098:Reproduction / Q000502:physiology*; D012621:Seasons; D019849:Sex Determination Processes; D012744:Sex Ratio; D013091:Spermatogenesis; D013093:Spermatogonia / Q000166:cytology; D013739:Testosterone / Q000031:analogs & derivatives / Q000097:blood; D014818:Vitellogenesis
D013739:Testosterone; D004958:Estradiol; C003600:11-ketotestosterone