Effects of exogenous estradiol-17β on early growth and gonadal development of diploid and triploid female rainbow trout (Oncorhyncus mykiss)

✍ Scribed by Krisfalusi, Michelle ;Cloud, J.G.

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 888 KB
• Volume: 19
• Category: Article
• ISSN: 0192-253X
• DOI: 10.1002/(sici)1520-6408(1996)19:4<302::aid-dvg3>3.0.co;2-d

✦ Synopsis

ASSTRACT Triploidy is a viable condition in teleosts. However, in many salmonids, the triploid condition in the female results in sterility as gametogenesis appears to be disrupted. Although the underlying mechanisms regulating the gonadal development of teleosts have not been clearly elucidated, the reversal of phenotypic sex by the administration of the appropriate exogenous steroid during early development supports the argument that gonadal steroids play a pivotal role in sexual differentiation and subsequent gonad development in these fish. To determine whether the failure of normal ovarian development in triploid female rainbow trout (Oncorhynchus mykiss) is due to an absence or reduction of endogenous sex steroids, ovarian morphology was compared between diploid and triploid juvenile rainbow trout treated with exogenous estradiolb17p (E2). The ovaries of both untreated and € 2 treated diploid fish, at 145 days post-fertilization, contained synchronously developing oocytes in the perinucleolar stage, whereas ovaries from untreated and estradiol-treated triploid fish of the same age were considerably smaller and devoid of developing ooqtes. No differences in the ovaries of triploid untreated fish and triploid fish treated with €2 were observed. It is reported that exposure to exogenous E2 during the period of gonadal differentiation is not sufficient to induce oocyte development in triploid rainbow trout.