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PubMed1994

Effects of photoperiod, pinealectomy, and melatonin implants on testicular development in juvenile Siberian hamsters (Phodopus sungorus).

When transferred from a long to short photoperiod, Siberian hamsters (Phodopus sungorus) undergo a number of physiological and morphological changes including suppression of gonadal activity, a change in pelage color, a decrease in body weight, and, in response to a simultaneous decrease in ambient temperature, physiological changes associated with the induction of daily torpor. All these functions can be affected by photoperiod and melatonin treatment. To investigate the interactive effects of photoperiod, pinealectomy, and melatonin on gonadal development, two experiments were performed using juvenile Siberian hamsters. In experiment 1, animals born in a long photoperiod (16L:8D) either remained in a long photoperiod or were transferred to a short photoperiod (8L:16D) from 15 days of age, when surgeries (pinealectomy and/or melatonin implantation) were performed. Testicular development was inhibited in all animals bearing melatonin implants irrespective of the presence or absence of the pineal gland. Pinealectomy blocked the inhibitory effect of short photoperiod on maturation of the reproductive system. Therefore, the pineal gland must be involved in the short photoperiod- induced inhibition of testicular maturation of juvenile Siberian hamsters. In experiment 2, a similar experimental design was employed except that the hamsters were born and raised to 15 days of age in 8L:16D. Exogenous melatonin, pinealectomy, or both retarded gonadal development in hamsters born in 8L:16D and transferred on Day 15 of age to 16L:8D. All hamsters maintained in a short photoperiod had small testes irrespective of the presence of absence of the pineal gland or of melatonin implants. Hamsters transferred to a long photoperiod after pinealectomy and/or melatonin implantation had small testes compared to those of the control group.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Bilateral large-cell calcifying Sertoli cell tumor of the testes with Peutz-Jeghers syndrome: a case report.

A 13-year-old boy with Peutz-Jeghers syndrome (PJs), gynecomastia, and bilateral multifocal testicular tumors is described. Histology of the testicular tissue disclosed large-cell calcifying Sertoli cell tumors. Females with PJs are known to be at increased risk of developing gonadal tumors. This case and a review of other reported cases suggest that males with PJs are also at risk for developing gonadal tumors.

Adolescent↗
PubMed1989

Seasonal variations in plasma and pituitary levels of gonadotrophin in males and females of two strains of rainbow trout (Salmo gairdneri).

Male and female rainbow trout of an autumn- and a winter-spawning strain were sampled every 28 days over a period of 2 years, starting when they were approximately 6 months old. Plasma and pituitary levels of gonadotrophin (GTH) were measured by a radioimmunoassay that preferentially detected the gonadotrophin referred to as either GTH II or "maturational and ovulatory" GTH. The general pattern of gonadal development and the profile of GTH in plasma and pituitary were similar in the two strains, except that the timing was different. Gonadal development in both sexes began about 9 months before spawning, concomitant with an increase in pituitary GTH content. In both sexes, pituitary GTH levels rose dramatically by about 50,000-fold, peaking at the beginning of spawning. They remained high many months thereafter, before falling slowly. Plasma GTH levels during the reproductive cycle were different in the two sexes. In both sexes plasma GTH levels remained very low and unchanged until shortly before full sexual maturity was reached. GTH levels then rose only slightly in males, but markedly in females. The slightly elevated GTH levels persisted many months in males, throughout the period when they could be stripped of milt, but in females they were elevated only a short time around ovulation. These results suggest that although a GTH II-like gonadotrophin is present in the pituitary gland throughout the period of gonadal growth, it does not appear to be released in any substantial amounts into the blood until near spawning.

Animals↗
PubMed1989

[Morphological observation on 6th-week development of human kidneys and gonads].

The development of kidney and gonad of 3-6th-week human embryos were studied. Their positions at different developing stages were measured in terms of the sequence of neural ganglion according to Felix's method. The 9.5 mm embryo: Pronephrons are seen as 2 epithelial blind tubules on the right side and 1 on the left at the 6th cervical ganglion level. The lateral tubule on the right side and the left one are pronephric ducts, whereas the medial one on the right side is the pronephric tubule. The cranial ends of mesonephrons on both sides level at the 1st thoracic ganglia and run caudally to the 11th thoracic ganglia, their total number amount to 62. The mesonephric ducts on both sides firstly appear opposite to the 1st thoracic ganglia and open caudally into the cloaca. The metanephrons, the ureteric buds are unbranched yet and the metanephric mesoderm appears as clusters of cells on both sides. The gonads are indifferent. The 11 mm embryo: Pronephrons degenerated. The cranial ends of mesonephric tubules locate at the 3rd thoracic ganglia level on both sides and extend caudally to the level of the 11th ganglion in the right side and 12th in the left, their total number amounts to 65. Mesonephric ducts appear opposite to the 4th thoracic ganglia on both sides, running caudally, and open into the cloaca. Metanephrons, the ureteric buds give off 1st grade branches on both sides and metanephric mesoderm remain as clusters of cells. The gonads are indifferent. The 12 mm embryo: Pronephrons degenerated.(ABSTRACT TRUNCATED AT 250 WORDS)

Gonads↗
PubMed1986

Testicular tumors with Peutz-Jeghers syndrome.

The case of a 6-year-old boy with Peutz-Jeghers syndrome (PJS), gynecomastia, and multifocal and bilateral testicular tumors is described. Females with PJS are known to be at increased risk for developing gonadal tumors. This case and other reports from the literature suggest that males, as well as females, with PJS are at risk for developing gonadal tumors.

Child↗
PubMed2003

Effects of 17alpha-ethynylestradiol in a partial life-cycle test with zebrafish (Danio rerio): effects on growth, gonads and female reproductive success.

In this study, the impact of an exposure of zebrafish embryos (Danio rerio) until 3 months post fertilization to 17alpha-ethynylestradiol (EE2: 0; 0,1; 1; 10; 25 ng/l) was evaluated for growth and development, gonad development and body vitellogenin (VTG) content. After a recovery period of 5 months, the female reproductive success was evaluated. The results demonstrated a significant reduction in total body length, body weight, whole body Ca and P content and an increase in morphological abnormalities for fish exposed to 25 ng/l EE2 as a function of exposure time. An increase in total body VTG content was observed for fish exposed for a period of 3 months down to levels of 1 ng/l EE2. At the age of 3 months, a dose-dependent increase of the number of fish with no macroscopic recognizable gonads was observed (up to 100% at 25 ng/l EE2). After a recovery period on clean tap water for 5 months, all fish had developed either ovaries or testis with a gonadosomatic index not different from control fish and the sex ratio was similar in EE2 treatment groups and controls. Nevertheless, a reduced number of spawning females and a reduced egg production were found for the female fish exposed to 10 or 25 ng/l EE2 for 3 months and which were allowed to recover for 5 months. Although the underlying mechanism could not be elucidated, these findings did indicate that the reproduction potential of fish populations might be disturbed by a long-term exposure to EE2 (> or =10 ng/l) from fertilization until sexual maturity.

Animals↗
PubMed2004

Sox8 is expressed at similar levels in gonads of both sexes during the sex determining period in turtles.

A critical gene involved in mammalian sex determination and differentiation is the Sry-related gene Sox9. In reptiles, Sox9 resembles that of mammals in both structure and expression pattern in the developing gonad, but a causal role in male sex determination has not been established. A closely related gene, Sox8, is conserved in human, mouse, and trout and is expressed in developing testes and not developing ovaries in mouse. In this study, we tested the possibility of Sox8 being important for sex determination or sex differentiation in the red-eared slider turtle Trachemys scripta, in which sex is determined by egg incubation temperature between stages 15 and 20. We cloned partial turtle Sox8 and anti-Müllerian hormone (Amh) cDNAs, and analyzed the expression patterns of these genes in developing gonads by reverse transcriptase-polymerase chain reaction and whole-mount in situ hybridization. While Amh is expressed more strongly in males than in females at stage 17, Sox8 is expressed at similar levels in males and females throughout the sex-determining period. These observations suggest that differential transcription of Sox8 is not responsible for regulation of Amh, nor responsible for sex determination in turtle.

Amino Acid Sequence↗
PubMed1988

Prolactin in the developing pig.

Prolactin (PRL) was determined in plasma of fetal pigs from 40 days post coitum (d.p.c.) onwards. Values increased in the last 3 wk of the gestational period and reached 10 ng/ml at term. Immunoreactive lactotropes could be identified as early as 31 d.p.c. Lactotrope development appeared to be biphasic, with no apparent increase in cell number in the 51-75 d.p.c. period. Sex differences in volume percentage of lactotropes and plasma PRL levels were observed in the 71-75 d.p.c. period. Pituitary PRL content increased 20-fold between 95 d.p.c. and term and 10-fold between birth and 6 wk. Volume percentage of lactotropes did not change from birth to 6 wk. In the postnatal period, plasma PRL concentrations were high in the first 1-2 wk and they decreased thereafter. Lower stable values were observed until about 10 wk, when PRL concentrations began to increase. Prepubertal peak levels were observed in the 10- to 16-wk period and a pubertal peak was observed at 20-22 wk. No significant differences between plasma PRL profiles of males and females were observed in the postnatal period. Castrated males, however, had consistently lower plasma PRL concentrations than intact boars. Cryptorchid boars had PRL concentrations comparable to intact boars. The PRL profile, in relation to the pattern of gonadal development, suggests a role for PRL in gonadal development of the pig.

Animals↗
PubMed1994

Effects of photoperiod and temperature on gonadal activity and plasma steroid levels in an autumn-spawning bitterling, Acheilognathus rhombea, during different phases of its annual reproductive cycle.

The kanehira bitterling, Acheilognathus rhombea, which breeds during autumn in the underyearlings and during summer and autumn in the yearlings, was exposed to various photoperiodic and temperature regimes during different phases of its annual reproductive cycle. In early autumn, gonadal development and increase in plasma levels of female estradiol-17 beta (E2) and male testosterone (T) of underyearling fish occurred under the short day length condition (12L12D). In early winter, gonadal regression (GSI reduction in both sexes, termination of vitellogenesis in females, and termination of spermatogonia proliferation in males) and decrease in plasma levels of E2 in females and T in males were induced by the low-temperature treatment (13 degrees), while gonadal maturity was maintained under the moderate temperature (20 degrees). The low temperature did not prevent oocyte maturation and ovulation in females and spermiogenesis and spermiation in males, indicating that temperature effect on gonadal activity is quite different among the maturational stages. The gonadal development of yearling fish did not progress during spring, even under the short day length condition combined with moderate temperature, which suggests that this species is in the refractory period during this season. In early summer, however, the autonomous gonadal maturation of yearling fish kept under moderate temperature progressed even under the long day length condition (15L9D). It is concluded that the causative factor in the initiation of the spawning period of the underyearling fish is the short day length in autumn, and that the causative factor in the termination of the spawning period is the low temperature in winter. An internal factor such as circannual rhythm in the yearlings is probably involved in the refractoriness to the photoperiod during spring and the subsequent earlier maturation during summer.

Animals↗
PubMed2003

Effect of cadmium on gonadogenesis and metamorphosis in Pleurodeles waltl (urodele amphibian).

In the amphibian Pleurodeles waltl, steroid hormones play a key role in sex differentiation. Since cadmium has been reported to block receptors of sex steroid hormones, we analyzed the effects of this heavy metal on Pleurodeles larvae gonadogenesis. At stage 42, larvae die in the presence of 10.9 microM Cd in the rearing tap water, with TL(50) of 46.3 h, but the concentration of 5.5 microM is tolerated for more than 60 days. When used at 5.5 microM cadmium accumulation measured by atomic absorption spectrophotometry (AAS) in total homogenates of larvae at stage 54 (after 77 days of exposure to the heavy metal) reached 58.1 microg/g of dry weight. At stage 54, we did not detect inhibitory effects on gonadogenesis in larvae reared in the presence of 5.5 microM Cd since stage 42. When the exposure to 5.5 microM Cd was lengthened after stage 54, metamorphosis was delayed and could not be completed. When larvae were exposed to 10.9 microM Cd from stage 54, metamorphosis did not occur and gonad development was stopped. Our study demonstrates a lack of a direct effect of cadmium on sex determination-differentiation but a strong inhibitory effect on metamorphosis, which impairs further gonadal development.

Analysis of Variance↗
PubMed2003

[Gonadic cycle of the American oyster Crassostrea virginica (Lamellibranchia: Ostreidae) in Mecoacán, Tabasco, México].

The American oyster Crassostrea virginica is exploited along Gulf of Mexico. This resource represents a job source and incomes for fishermen. In Mexico the production is supported by Tabasco state, the first producer. However, the mexican landings of this bivalve had been dropped about 40% last ten years. By 1999, Tabasco presents a unique ban season fishery of oysters. This season was based in evaluation of gonadal development by visual observations of color and texture, larvae and seeds abundance. In 2000, the government set up two ban seasons in terms of evaluation of populations every year, without gonadal analysis. In general, exists different spawning seasons for American oyster, in accordance with the environmental conditions. It is necessary to establish a ban season according to reproductive cycle. This study presents the gonadic cycle for an oyster population of Mecoacin lagoon along a year. It was defined five phases of the gonad development: resting, gametogenesis, mature or ripe, spawn and post spawn. Gametogenesis is present all the year, except December. The spawning activity was detected all year, except July and August. The ripe phase presented maximum values in August and December. It was proposed a modification of the ban seasons from April 15 - May 30, and September 15 - October 30 to March 15 - May 15 and September 1 - October 30, respectively, according to gonadic cycle obtained in this work. This modification would to avoid capture mature organisms (ready to spawn).

Animals↗
PubMed2002

Timing of exposure to a pulp and paper effluent influences the manifestation of reproductive effects in rainbow trout.

Rainbow trout were exposed to a secondary treated, thermomechanical/bleached kraft pulp and paper effluent in 12,000-L, flow-through exposure tanks at an environmental research facility located at a pulp and paper mill in Kawerau, New Zealand. Trout (age, 2+ years) were obtained from a local hatchery and exposed either to upstream river water or a nominal concentration of 12% (v/v) effluent diluted in upstream river water. Three treatment groups were used: Effluent exposure that started approximately three months before gonadal growth (eight-month total exposure), effluent exposure that started approximately halfway through gonadal development (two-month total exposure), and trout exposed to reference water alone for the total duration of the experiment. Trout were sacrificed just before spawning; exposure, growth, and reproductive endpoints were assessed during and at the termination of the experiment. Reduction in growth was observed in both sexes in the eight-month treatment group relative to the river water reference treatment group. No differences were observed in condition factor or liver size in either treatment. Females in the eight-month exposure group also had significantly lower ovary weight. The two-month exposure group showed no differences from the reference group in growth or somatic indices. Estradiol and testosterone were reduced in blood samples taken from the eight-month exposure group by four months into the experiment as compared to the reference treatment. Steroid and vitellogenin levels in individual female trout from this treatment were significantly correlated with gonadosomatic indices (GSI) measured at the termination of the experiment. The GSI was not correlated strongly or consistently with pregnenolone, nor were any treatment-related pregnenolone differences observed, indicating that the steroid hormone reductions likely were not related to cholesterol side-chain cleavage. Male trout showed significant induction of vitellogenin and lower 11-ketotestosterone during the experiment (only the eight-month group was examined), but this did not result in any significant differences in testes development. Thus, this study has shown an impact of pulp mill effluent exposure on the reproductive physiology of female trout that appeared to be hormonally mediated. Furthermore, the effect could only be manifest when the exposure was initiated before the start of gonad development.

Animals↗
PubMed2003

Retina-type rhodopsin gene expressed in the brain of a teleost, ayu (Plecoglossus altivelis).

Ayu (Plecoglossus altivelis) is a teleost whose gonadal development is stimulated by shortened daylength and is a useful model to study the mechanism of photoperiodism. However, localization and characteristics of the photoreceptor that mediates photoperiodism in gonadal development remain to be determined. To identify the photoreceptive molecule that regulates photoperiodic responses, in the present study, we have cloned and characterized the cDNA encoding an opsin gene expressed in the ayu brain, a putative site of the photoreceptor for photoperiodism. The identified opsin was rhodopsin that is identical to the rhodopsin expressed in the retina. Phylogenetic analysis demonstrated that this rhodopsin belongs to the retina-type but not to the pineal-specific rhodopsin group. Genomic polymerase chain reaction (PCR) demonstrated that the ayu rhodopsin gene is intron-less. Southern and Northern blots and reverse-transcription PCR analyses indicate that the same rhodopsin gene is expressed in the retina and the brain but not in the pineal organ of ayu. These results indicate that the rhodospin gene is expressed in the retina and brain and mediates not only visual but also nonvisual functions such as photoperiodism and entrainment of the circadian clock.

Amino Acid Sequence↗
PubMed2002

Sex-determining genes in mice: building pathways.

Sry is active in the mouse for a very brief period in somatic cells of the genital ridge to initiate Sertoli cell differentiation. SRY protein must act within the context of other gene products required for gonadal development and must itself act on one or more target genes that will ensure the further differentiation and maintenance of Sertoli cells. Over the last few years several genes have been found that have important roles in gonadal development and sex determination. These include genes encoding transcription factors such as Lhx9, Wt1, Sf1, Dax1, Gata4, Dmrt1 and Sox9, and some involved in cell cell signalling, including Amh, Wnt4 and Dhh. While more await discovery, it is now possible to start putting some of the known genes into pathways or networks. Sox9 probably occupies a critical role in mammals for both the initiation and maintenance of Sertoli cell differentiation. Data will be presented that are consistent with SRY acting directly on Sox9 to ensure its up-regulation. SF1 is also central to gonadal differentiation. Our results imply that it contributes to transcriptional activation of several relevant genes, not just those required for male development, including Sox9 and Amh, but also those that can have an antagonistic effect on Sertoli cell differentiation, such as Dax1. Progress in establishing other regulatory interactions will also be discussed.

Animals↗
PubMed1978

Hemagglutinins in female fish gonads: comparative investigations on perch (Perca fluviatilis) gonads of different stages of development.

Female gonads of the perch (Perca fluviatilis) in various stages of development are tested for hemagglutinin activity against human erythrocytes. Based on the different agglutination patterns obtained, and on inhibition tests with L-fucose and a mature gonad of a male perch, the appearance two different agglutinins in the course of the development of the female gonad is assumed.

Agglutinins↗
PubMed2003

Physiological costs of reproduction in the Sydney rock oyster Saccostrea glomerata. How expensive is reproduction?

In this study, triploid Sydney rock oysters Saccostrea glomerata, which do not reproduce and have only limited gonadal development, were used to calculate the cost of producing and maintaining somatic tissues. The consumption of oxygen was measured and converted to units of energy expended. The consumption of oxygen of diploid oysters, in different stages of the reproductive cycle, was also measured. Knowing the costs of producing and maintaining somatic tissues (obtained from the triploid oysters), it was possible to calculate the energy demand of somatic and reproductive tissues of diploid oysters. The focus of this study was to test whether this method would work, to investigate if this method would give results in accordance with modern life-history theory and to test hypotheses about costs of reproduction in oysters. It was found that in diploid oysters, 27% of the consumed oxygen was needed for reproductive processes. It was also found that the costs of production and maintenance of reproductive tissues were on average 84% of those of somatic tissues. Costs for the production and maintenance of somatic tissues decreased over time. Costs for reproduction also decreased, but were dependent on the stage of gonadal development. If the relative mass of gametes in the gonads was large, the costs were relatively small; if the mass was relatively small, the costs were large. Differences between traits of males and females were never significant, suggesting that reproductive effort and costs were similar in males and females. It was estimated that if diploid oysters did not reproduce, they could gain 64% more somatic ash-free dry mass. Thus, in terms of growth, reproduction is an expensive activity.

Animals↗