title: Sex steroid levels in the testes, ovaries, and pyloric caeca during gametogenesis in the sea star Asterias vulgaris.
abstract: The concentrations of progesterone, testosterone, and estradiol were determined via radioimmunoassay in testes, ovaries, and pyloric caeca of the sea star Asterias vulgaris during one complete and two partial gametogenic cycles. These compounds were found in all tissues examined and were present in quantities similar to those reported previously in other echinoderms and in vertebrates. Testes and ovaries exhibited annual growth cycles during which testicular and ovarian mass increased up to 100-fold as gametes were produced and stored until spawning. Pyloric caecal mass varied during the annual reproductive season; however, no seasonal trends were apparent. In the testes, sex steroid levels were highest at the onset of spermatogenesis. Transient increases in the levels of estradiol coincided with spermatogonial mitotic proliferation. Transient increases in the levels of testosterone and progesterone in the testes coincided with spermatogenic column formation and with spermiogenesis, respectively. In the ovaries, estradiol and testosterone levels were highest at the onset of oogenesis while progesterone levels did not change significantly throughout the annual gametogenic cycle. Male and female pyloric caeca exhibited similar seasonal variations in levels of sex steroids as compared with the gonads. It is hypothesized that transient increases in the levels of sex steroids during gametogenesis may serve as endogenous modulators of reproduction.
authors.affiliation: Department of Biology, University of Alabama, Birmingham 35294.
authors.forename: G A
authors.initials: GA
authors.lastname: Hines
authors.forename: S A
authors.initials: SA
authors.lastname: Watts
authors.forename: S A
authors.initials: SA
authors.lastname: Sower
authors.forename: C W
authors.initials: CW
authors.lastname: Walker
mesh_terms: D000818:Animals; D002432:Cecum / Q000378:metabolism; D004447:Echinodermata / Q000378:metabolism*; D005260:Female; D005718:Gametogenesis; D012739:Gonadal Steroid Hormones / Q000378:metabolism*; D008297:Male; D010053:Ovary / Q000254:growth & development / Q000378:metabolism; D012621:Seasons; D013696:Temperature; D013737:Testis / Q000254:growth & development / Q000378:metabolism
chemical_list: D012739:Gonadal Steroid Hormones