Particularities of reproduction and oogenesis in teleost fish compared to mammals

Abstract

-Compared to mammals, teleost reproduction presents many original features. Reproductive strategies of species are diversified into numerous adaptations to a large variety of aquatic environments. This diversity may concern sexuality, spawning and parental behaviour, sensitivity to environmental factors, and specific features of gametogenesis such as the duration of vitellogenesis, and egg morphology. Sexuality presents a variety of natural modalities, from gonochorism to hermaphrodism. The absence of definitive arrest of body growth in the adult of most species gives a particular interest to the practical control of growth-reproduction interactions. Vitellogenesis, which represents an important metabolic effort for the maternal organism, involves the synthesis of vitellogenin, a specific glycolipo-phosphoprotein produced in the liver under estradiol stimulation, and its incorporation into oocytes by a receptor mediated process. Both estradiol synthesis in follicle cells and vtg uptake by vitellogenic follicles appear to be mainly controlled by FSH. Oocyte maturation is directly triggered by a progestin, or MIS (maturation inducing steroid) synthesised in follicle cells mainly under LH control, and acting through the non-genomic activation of a membrane receptor. Practical applications of some of these particularities result mainly from the external character of the fertilisation process and of embryonic development, which allows manipulating respectively egg chromosome stocks and sex differentiation. Moreover, the sensitivity of sex differentiation to exogenous factors favours the development of practical methods to control the sex of farmed populations. Finally, the sensitivity of reproductive mechanisms to xenobiotics has led to various kinds of bioassays for putative pollutants.reproductive strategies / sexuality / spawning / vitellogenesis / oocyte maturation / fertilisation

Reproductive apparatus and gametogenesis of Lophiosilurus alexandri Steindachner (Pisces, Teleostei, Siluriformes)

“…According to BAZOLLI & GODINHO (1997), these structures contain neutral glycoproteins that are released into the perivitellinic space in order to block polyspermy after fertilization (MICALE et al 1999). During secondary growth, the oocyte increases its diameter due to the accumulation of yolk (JALABERT 2005). It was observed that the vitellogenic oocytes in L. alexandri increased their diameter in ca.…”

Molecular basis and genetic improvement of economically important traits in aquaculture animals

“…In comparison with mammals, fish reproduction modes and strategies exhibit abundant diversities and extreme particularities [49,50]. Owing to the diversities and particularities, much attention has begun to be paid to some important fish with special reproduction modes.…”

Influence of ovarian stage on transcript profiles in fathead minnow (Pimephales promelas) ovary tissue

“…Oocytes, and their surrounding follicular cells, representing different stages of follicle development, both produce and respond to different types of signaling molecules during maturation (Jalabert, 2005;Lubzens et al, 2009), and thus would be expected to have different transcription profiles depending on their relative stage of maturation. Consequently, when studying the effects of chemical contaminants or other stressors on ovarian transcript profiles, chemical effects must be interpreted over a background signal which is dependent on the relative number and proportions of different staged follicles present within the ovary.…”