The Seminal Vesicles and Testes of Gillichthys, a Marine Teleost

GLANDULAR structures accessory to the testes of some fish have received scant attention. So-called seminal vesicles were noted as early as 1824 by Rathke in Gobius niger. The double seminal vesicles of Mullus barbatus, Gobius jozzo, G. minutus, G. panganellus and the single vesicle of Cobitis fossilis were briefly described by Hyrtl (1850). An excellent study of the sexual organs of several species of gobies and blennies was made by Eggert (1931). He reported in detail the structure and histology of the seminal vesicle of Periophthalmus chrysospilos. In Esox lucius, Disselhorst (1904) recognized similar structures, but only in large males during spawning time. Gilbert (1943) gave an account of the seminal vesicles of Chlamydoselachus. The male mudsucker, Gillichthys mirabilis, has well developed accessory sex organs. Although this fish is common in the bays and estuaries along the Pacific coast of the United States, the testes and vesicles have not been previously described. This report also includes observations on the seasonal changes in the testes and vesicles, the possible function of the vesicular fluid, and the response of the vesicles to testosterone.