Abstract
The oogenesis is a key stage in the reproductive development of an organism, which can be best understood from histological analysis of ovaries in different maturity stages. In order to provide information on the reproductive biology of the black triggerfish, M. niger, in particular on its oogenesis process, this study aimed at identifying and characterizing the oocyte development stages and its organization within the different stages of ovarian maturation based on specimens from São Pedro e São Paulo Archipelago. In this present report, a number of 294 ovaries were histologically analyzed. It was verified that they are composed of ovigerous lamellae containing oocytes at different development stages. Five different stages of oogenesis were identified: young cells, with an average size of 12.9 ìm; previtellogenic oocytes (perinucleolar), with an average size of 53.5 ìm; cortical-alveoli oocytes with an average size of 83.1 ìm; vitellogenic oocytes, with an average size of 160.4 ìm and mature oocytes, with an average size of 289.8 ìm. In addition to the germ cells, some somatic structures were also identified, such as: ovarian wall, follicular cells and blood vessels. Based on the type and number of oocytes observed, four stages of ovarian maturation were identified: early maturation, represented by only 2.2% of the sample; middle maturation, represented by 9.9%; mature, represented by 44.2% and resting, represented by 43.9%. The identification of five oocyte development stages in the ovarians from M. niger, suggested that the specie follows a pattern similar to that described for other marine fish.
Highlights
Most studies conducted so far on the reproductive biology of teleosts are related to macroscopic classification of maturity stages of gonads, gonadosomatic index (GSI), fecundity and reproductive behavior of species in natural environment, including mating and spawning behavior (Fricke, 1980; Hunter & Macewicz, 1985; Kawase, 2003; Abascal & Medina, 2005)
In order to overcome this deficiency, the present study aimed to identify and characterize the oocyte development stages of black triggerfish and its organization throughout the different stages of ovarian maturation, based on specimens from São Pedro e São Paulo Archipelago (SPSPA), area in which the species usually spawns seasonally, especially in the first semester of the year (Branco, 2011)
The ovaries of black triggerfish, M. niger, examined in this study were morphologically and structurally similar to those observed in most teleosts (Jalabert, 2005)
Summary
Most studies conducted so far on the reproductive biology of teleosts are related to macroscopic classification of maturity stages of gonads, gonadosomatic index (GSI), fecundity and reproductive behavior of species in natural environment, including mating and spawning behavior (Fricke, 1980; Hunter & Macewicz, 1985; Kawase, 2003; Abascal & Medina, 2005). Histological analysis is an essential tool to reach this goal. It uses microscopic classification of developmental stages of ovaries, including their cytological characteristics, is especially important to identify the reproductive activity of tropical reef species, during non-spawning periods (Tricas & Hiramoto, 1989). The oogenesis process has already been well described for some teleost species (Wallace & Selman, 1981; McMillan, 2007), as of yet there is little information available on oocyte development of species of the family Balistidae, except for Balistes capriscus (Bernardes & Dias, 2000)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
