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Journal ArticleDOI

Circannual changes in morphological, ultrastructural and hormonal activities of the ovary of an estuarine grey mullet, Mugil cephalus L.

01 Aug 2013-Biological Rhythm Research (Taylor & Francis)-Vol. 44, Iss: 4, pp 541-567
TL;DR: It is concluded that FSH, PRL, E2 and testosterone trigger oocyte growth in pre-breeding, and LH and DHP cause further growth and oocyte maturation in breeding.
Abstract: The objective of this study was to investigate the circannual ovarian cycle month-wise round the year at morphological, ultrastructural and hormonal levels in an estuarine teleost, the grey mullet Mugil cephalus L. The gonadosomatic index and follicular population per ovary began to rise from September to October (pre-breeding), reached peak during November and December (breeding) and declined from January to August (post-breeding phase). Oocyte diameter increased during pre-breeding, attained maximum size in breeding and drastically reduced in post-breeding phase. But the follicular populations per milligram of ovary per microscopic field were moderately high in pre-breeding, least in breeding and highest in post-breeding. Histologically, the ovarian lobules were moderately large and contained small and large follicles in pre-breeding, maximally enlarged with mostly large follicles in breeding and became narrow with very small follicles in post-breeding. Ultrastructurally, three types of oocytes (1) smal...
Citations
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Journal ArticleDOI
TL;DR: In this paper, the grey mullet Mugil cephalus is one of the popular and fast growing fishes being cultured in tropical and subtropical regions, and histological observation of gonadal development and corresponding changes in sex steroid levels from different maturity stages of wild caught male and female were studied.
Abstract: The grey mullet Mugil cephalus is one of the popular and fast growing fishes being cultured in tropical and subtropical regions. In the present study, histological observation of gonadal development and corresponding changes in sex steroid levels from different maturity stages of wild caught male and female were studied. In female, testosterone and 17β-estradiol increased with the advancement of maturation and reached peak (17β-estradiol, 323 ± 13 pg/ml; testosterone, 938 ± 7.87 pg/ml) in mature stage, whereas the level of progesterone was maximum (488 ± 4.9 pg/ml) during ripe stage. Vitellogenin level in serum showed a similar trend as 17β-estradiol. In case of male, the testosterone level in serum increased gradually with advancement of maturation and was maximum (1820 ± 40.25 pg/ml) during ripe stage, whereas significant decrease in 17β-estradiol and progesterone was noticed with advancement of maturation. The fundamental information from this investigation would be useful for developing protocol for a...

14 citations


Cites background or result from "Circannual changes in morphological..."

  • ...Das et al. (2014) in M. cephalus....

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  • ...A sudden drop in the plasma E2 level from vitellogenic (mature) to post-vitellogenic (ripe) stage may be explained in terms of switching off the aromatase (CYP19) activity as oocytes progressed to final maturation that is parallel to the observation made by Das et al. 2014 in M. cephalus....

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  • ...In case of female, left ovary was longer than the right ovary, which is similar to the observation made by Das et al. 2014....

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  • ...Correlation between changes in plasma levels of steroids and oocyte development have been documented in grey mullet by Das et al. 2014, and the reproductive periodicity of gonadal steroid hormone level has been studied in wild caught mullet by Yelghi et al. 2012....

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Journal ArticleDOI
TL;DR: DHP is the most potent inducer of oocyte maturation in Indian estuarine flat head grey mullet and Interplay of several hormones (hCG, LH, and probably E2 and testosterone) and IGF-I on oocytes maturation is suggested in the mullet.
Abstract: In this article, an in vitro investigation was carried out to ascertain the roles of hormones and growth factor in the inductions of oocyte maturation and steroidogenesis of the postvitellogenic follicles in an Indian estuarine grey mullet, Mugil cephalus L. Oocyte maturation was evaluated by scoring the germinal vesicle breakdown (GVBD) percent of the postvitellogenic follicles. All the sex [17α,20β-dihydroxy-4-pregnane-3-one (DHP), estradiol 17β (E2), progesterone (P), 17α-OH progesterone (17-OH-P) and testosterone] and other [bovine-insulin and salmon-calcitonin, human chorionic gonadotropin (hCG), luteinizing hormone (LH) or hCG+DHP] hormones and insulin-like growth factor-I (IGF-I) significantly increased GVBD% in 9 h culture. DHP had a maximum effect (75 %) compared to other effectors. Some effectors (hCG: 82.14 %, LH: 78.94 %, hCG plus DHP: 81.81 %, E2: 80 % and IGF-I: 74.19 %) including DHP (79 %) further increased GVBD% in 15-h culture. All the hormones (except DHP) and IGF-I increased DHP, E2 and testosterone productions by the postvitellogenic ovarian follicles in vitro. DHP and testosterone productions were increased with the increase of incubation time from 9 h through 15 h. E2 production was not further increased beyond 12 h. DHP production was highest by hCG compared to other effectors. The hCG of all the test compounds was most effective in both the induction of GVBD% and steroid production. DHP is the most potent inducer of oocyte maturation in Indian estuarine flat head grey mullet. Involvement of estrogen in mullet oocyte maturation is indicated. hCG, like DHP, is equally potent and induces oocyte maturation via DHP production in vitro. hCG with DHP has synergistic action on oocyte maturation in mullet ovary. Interplay of several hormones (hCG, LH, and probably E2 and testosterone) and IGF-I on oocyte maturation is suggested in the mullet.

12 citations


Cites background from "Circannual changes in morphological..."

  • ...circannual ovarian cycle of the flat head grey mullet, which is available online (Das et al. 2012)....

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  • ...We have already worked out the circannual ovarian cycle of the flat head grey mullet, which is available online (Das et al. 2012)....

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Journal ArticleDOI
TL;DR: Beta-mimetic treatment is indicated in multiple pregnancies even in false labor, or when painless progress in cervical dilatation is observed, to avoid asymptomatic progression into true labor.
Abstract: Modern treatment for anovulatory infertility increases the incidence of multiple pregnancies with three or more fetuses and predisposes to prematurity with high perinatal mortality and mortidity. Premature labor was successfully treated in four multifetal pregnancies with ritodrine hydrochloride, a beta-mimetic drug relaxing the uterus. Another patient misdiagnosed as false labor was not treated and lost three out of four premature babies. Beta-mimetic treatment is indicated in multiple pregnancies even in false labor, or when painless progress in cervical dilatation is observed, to avoid asymptomatic progression into true labor. In contrast to singleton pregnancies, advanced labor with more than four centimeters cervical dilatation should not preclude good chances for successful treatment. Persistence in treatment and repreated use of the most effective intravenous route combined with oral ritodrine administration is needed because of marked tendency to recurrences of premature labor. Progressive increase in the dose of oral ritodrine may be indicated by decrease in therapeutic response. Maternal tachycardia should be considered as an index of patient responsiveness to the beta-mimetic treatment. The therapy is most successful when the patient is hospitalized from the first episode of treatment until at least the 37th week of pregnancy. This is probably less expensive than prolonged hospitalization of several prematures in an intensive care nursery.

5 citations

Book ChapterDOI
01 Jan 2021
TL;DR: In this article, two peaks of gonadotropins (FSH and LH) are observed in the plasma of multiple spawner female fish (tilapia) during two consecutive spawning.
Abstract: The development of captive broodstock and reproductive maturation is essential for induced breeding. The reproductive cycle of fish is divided into two phases, that is, growth and maturation phase, which is controlled by the cascade of hormones along the brain-pituitary-gonad (BPG) axis. In this axis, gonadotropin-releasing hormone (GnRH) and dopamine secreted from the brain regulate the gonadotropin secretion from the pituitary. The gonadotropins from the pituitary gland are released into the blood which act on the gonad to trigger the production of the sex steroid hormones. Estradiol-17β (E2) under the control of gonadotropin (follicle-stimulating hormone, FSH) regulates the vitellogenesis and oocyte growth. Maturation-inducing steroid (MIS) or maturation-inducing hormone (MIH) under the control of gonadotropin (luteinizing hormone, LH) regulates the maturation and spawning. In synchronous fish, the level of FSH increases during the vitellogenic phase and drops during follicular maturation and spawning, whereas the LH level is low at vitellogenesis and high before ovulation. The first peak of testosterone occurred during vitellogenesis, and the second peak is observed just prior to spawning. The E2 level remains high during late-vitellogenic and vitellogenic stages and low during post-vitellogenic and hydrated stages. In male, FSH increases gradually at the initial stage of spermatogenesis, reaches peak during testicular growth, and then declined after spawning, whereas LH is low at early spermatogenesis, increases during spermiation, and attained peak during the spawning. In male, the first peak of testosterone is noticed during pre-spawning and the second just prior to the spawning. In asynchronous fish, two peaks of gonadotropins (FSH and LH) are observed in the plasma of multiple spawner female fish (tilapia) during two consecutive spawning. The first peak is evident 2 to 3 days after spawning (vitellogenic phase), and the second peak is noticed just before the next spawning. The knowledge on hormonal cycle will help in the captive breeding of fishes.

1 citations

References
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Journal ArticleDOI
TL;DR: It is indicated that leptin plays an important role in controlling gonadotropin secretion by stimulatory hypothalamic and pituitary actions.
Abstract: A defect in the structure of the obese gene is responsible for development of obesity in the ob/ob mouse. The product of expression of the gene is the protein hormone leptin. Leptin causes weight loss in ob/ob and normal mice, it is secreted by adipocytes, and it is an important controller of the size of fat stores by inhibiting appetite. The ob/ob mouse is infertile and has a pattern of gonadotropin secretion similar to that of prepubertal animals. Consequently, we hypothesized that leptin might play a role in the control of gonadotropin secretion and initiated studies on its possible acute effects on hypothalamic–pituitary function. After a preincubation period, hemi-anterior pituitaries of adult male rats were incubated with leptin for 3 hr. Leptin produced a dose-related increase in follicle-stimulating hormone (FSH) and luteinizing hormone (LH) release, which reached peaks with 10−9 and 10−11 M leptin, respectively. Gonadotropin release decreased at higher concentrations of leptin to values indistinguishable from that of control pituitaries. On the other hand, prolactin secretion was greatly increased in a dose-related manner but only with leptin concentrations (10−7–10−5 M). Incubation with leptin of median eminence–arcuate nuclear explants from the same animals produced significant increases in LH-releasing hormone (LHRH) release only at the lowest concentrations tested (10−12–10−10 M). As the leptin concentration was increased, LHRH release decreased and was significantly less than control release at the highest concentration tested (10−6 M). To determine if leptin can also release gonadotropins in vivo, ovariectomized females bearing implanted third ventricle cannulae were injected with 10 μg of estradiol benzoate s.c., followed 72 hr later by microinjection into the third ventricle of leptin (0.6 nmol in 5 μl) or an equal volume of diluent. There was a highly significant increase in plasma LH, which peaked 10–50 min after injection of leptin. Leptin had no effect on plasma FSH concentrations, and the diluent had no effect on either plasma FSH or LH. Thus, leptin at very low concentrations stimulated LHRH release from hypothalamic explants and FSH and LH release from anterior pituitaries of adult male rats in vitro and released LH, but not FSH, in vivo. The results indicate that leptin plays an important role in controlling gonadotropin secretion by stimulatory hypothalamic and pituitary actions.

732 citations


"Circannual changes in morphological..." refers background in this paper

  • ...LH cells during pre-spawning reported in most of the teleosts studied (Yu et al. 1997)....

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Journal ArticleDOI
TL;DR: Vitellogenesis, the process of yolk protein synthesis, transport, and uptake into the oocytes, and zonagenesis, the synthesis of eggshell zona radiata proteins, their transport and deposition by the maturing oocyte, are important aspects of oogenesis.
Abstract: The oocyte is the starting point for a new generation. Most of the machinery for DNA and protein synthesis needed for the developing embryo is made autonomously by the fertilized oocyte. However, in fish and in many other oviparous vertebrates, the major constituents of the egg, i.e. yolk and eggshell proteins, are synthesized in the liver and transported to the oocyte for uptake. Vitellogenesis, the process of yolk protein (vitellogenin) synthesis, transport, and uptake into the oocyte, and zonagenesis, the synthesis of eggshell zona radiata proteins, their transport and deposition by the maturing oocyte, are important aspects of oogenesis. The many molecular events involved in these processes require tight, coordinated regulation that is under strict endocrine control, with the female sex steroid hormone estradiol-17β in a central role. The ability of many synthetic chemical compounds to mimic this estrogen can lead to unscheduled hepatic synthesis of vitellogenin and zona radiata proteins, with potentially detrimental effects to the adult, the egg, the developing embryo and, hence, to the recruitment to the fish population. This has led to the development of specific and sensitive assays for these proteins in fish, and the application of vitellogenin and zona radiata proteins as informative biomarkers for endocrine disrupting effects of chemicals and effluents using fish as test organisms. The genes encoding these important reproductive proteins are conserved in the animal kingdom and are products of several hundred million years of evolution.

470 citations


"Circannual changes in morphological..." refers background in this paper

  • ...Estradiol induces hepatocytes to produce vitellogenin, which is sequestered by the oocytes in a receptor-mediated process enhanced by GtH-I (FSH) (Arukwe and Goksoyr 2003)....

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  • ...Fifty microliters of the appropriate serum reference and test samples containing FSH were added to the assigned wells....

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  • ...One-hundred microliters of FSH-enzyme conjugate solution were added to each well....

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  • ...It is concluded that FSH, PRL, E2 and testosterone trigger oocyte growth in pre-breeding, and LH and DHP cause further growth and oocyte maturation in breeding....

    [...]

  • ...Serum luteinizing hormone (LH) (mIU/ml) was quantitated by IEMA/ELISA using an assay kit (Eliscan LH, RANBAXY, India) as followed for FSH (Kosasa 1980)....

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Book
08 Jan 1976
TL;DR: The third edition provides a description of hormones in animals and considers their evolution and roles in coordinating bodily functions and the control of calcium, water and salt levels in the body.
Abstract: The third edition of this popular textbook retains the successful format of previous editions, dealing with the nature, actions and roles of hormones among vertebrate animals. Special emphasis is placed on the evolution and origins of hormones and their receptors, on the role of hormones in the physiological coordination of vertebrates, and on dealing with each endocrine process in the context of the organism's physiology, ecology and evolution. Comparative Vertebrate Endocrinology discusses the intimate physiology of the endocrine system and the pivotal role of hormones in coordinating basic body processes such as nutrition, reproduction, calcium metabolism and osmoregulation, as well as their contributions to animal coloration, molting and development. The species included range from lower chordates through to mammals, including marsupials.

346 citations

Journal ArticleDOI
01 Jan 1997-Steroids
TL;DR: Findings suggest that 17 alpha,20 beta-DP initiates translation of cyclin B mRNA through cytoplasmic 3' poly(A) elongation.

330 citations

Journal ArticleDOI
TL;DR: This review summarizes the major neuroendocrine mechanisms regulating ovulation, thus providing a basis for understanding the various environmental and hormonal techniques for induction of ovulation of cultured teleosts.
Abstract: This review summarizes the major neuroendocrine mechanisms regulating ovulation, thus providing a basis for understanding the various environmental and hormonal techniques for induction of ovulation of cultured teleosts. The secretion of gonadotrophin-ii(GtH-ii) is stimulated by gonadotrophin-releasing hormone (GnRH), and, although some teleosts have three different forms of GnRH regionally distributed in the brain, in most species investigated, only one form is present in the pituitary and apparently involved in GtH-ii secretion. In nearly all species investigated, dopamine (DA) inhibits GtH-ii secretion by direct actions on gonadotrophs, as well as by inhibition of GnRH release. Sex steroids act at both brain and pituitary levels to regulate GtH-ii secretion through a combination of positive and negative feedback actions; one important positive feedback action is that sex steroids enhance the responsiveness of the pituitary to GnRH and an important negative feedback action is to increase DA turnover, thereby increasing the overall DA inhibitory tone on GtH-ii secretion. The preovulatory surge of release of GtH-ii is stimulated by a surge release of GnRH. A decrease in DA turnover also occurs to disinhibit GnRH and GtH-ii release. Environmental factors including photoperiod, temperature and spawning substrate may cue ovulation and spawning. Social and pheromonal interactions play a very important role in synchronizing preovulatory endocrine changes, ovulation and spawning behaviour in many species. A widely used technique for inducing ovulation of cultured fishes is injection of the combination of a GnRH superactive analogue, to stimulate GtH-ii release, and a DA receptor antagonist, to block the inhibitory actions of DA. This is termed the Linpe technique and has proven particularly useful with those species having synchronous or group synchronous follicular development and a large preovulatory surge of GtH-ii. In other groups of teleosts, particularly those species having asynchronous ovarian development and multiple spawnings over an extended period, treatment with a sustained-release preparation of a GnRH superactive analogue to cause a prolonged, somewhat enhanced release of GtH-ii has proven highly successful in inducing multiple ovulations and spawnings. However, the lack of specific radioimmunoassays for GtH-ii in many of these species has hindered progress, as the precise pattern of GtH-ii release necessary for the recruitment of vitellogenic oocytes into final maturation and ovulation in these multiple spawners remains an intriguing neuroendocrine question

258 citations