Abstract
The present work aimed to identify the best doses of human chorionic gonadotropin (hCG) needed to induce oocyte maturation of Micropogonias furnieri and to characterize ovarian dynamics during the periovulatory period. Adult M. furnieri females with fully developed ovaries were injected intraperitoneally with four different doses of hCG. The gonadotropin response was succeeded by analyzing morphologically gonadal biopsies and following the postinjection changes in follicle diameter. Oocyte maturation was induced by three doses used: 100, 300, and 500 IU of hCG kg bw-1, and was reached 48 h after treatment with 300 and 500 IU of hCG kg bw-1, and 72 h after treatment with 100 IU of hCG kg bw-1. Concerning ovarian dynamics, only 100 and 300 IU of hCG kg bw-1 mimicked the natural ones which have a synchronic group maturation. In conclusion, the dose mimicking natural ovarian dynamics and inducing oocyte maturation more quickly is 300 IU of hCG kg bw-1.
Highlights
The white croaker (Micropogonias furnieri, Desmarest, 1823) is a teleost fish widely distributed on the Atlantic coast (Vazzoler, 1998) and important as a fishery resource to Uruguay and Argentina (40.000 ton yr–1)
Successful spawning and oocyte maturation were induced by mammalian gonadotropins, by the human chorionic gonadotropin on different species (Donaldson & Hunter, 1983; Donaldson, 1996; Patiño, 1997)
Definition of oocyte maturation stages Five morphological oocyte stages were recognized after analysis under light microscopy (Fig. 2): Pre-vitellogenic oocytes presented a spherical or polygonal shape
Summary
The white croaker (Micropogonias furnieri, Desmarest, 1823) is a teleost fish widely distributed on the Atlantic coast (Vazzoler, 1998) and important as a fishery resource to Uruguay and Argentina (40.000 ton yr–1). Nion (1985) reported that the stock was fully exploited during the 1980s and Arena (1990) confirms that captures have reached the maximum sustainable level for continued exploitation. The white croaker (Micropogonias furnieri, Desmarest, 1823) is a teleost fish widely distributed on the Atlantic coast (Vazzoler, 1998) and important as a fishery resource to Uruguay and Argentina (40.000 ton yr–1). In several commercial species of Sciaenidae (Perciforms), hCG was successfully used with to induce oocyte maturation (Thomas, 1994). Few data are available on hormonal induction of oocyte maturation of M. furnieri and it is not known which is the best hormone dose for obtaining optimum maturity response. The objective of this study was to contribute to the understanding of the maturation response process of the female croaker (M. furnieri) kept in captivity and to determine the hCG dose needed to obtain mature gametes
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