Histological Analysis Of Gonads Research Articles

Estimación de la proporción de sexos de neonatos de tortuga charapa (Podocnemis unifilis) mediante morfometría del caparazón, en la Amazonía ecuatoriana

Una de las causas de la declinación de poblaciones de Podocnemis unifilis es la captura y consumo de hembras adultas y sus huevos; por esta presión, existen varios programas de manejo comunitario, los cuales mediante incubación, crianza y liberación de juveniles intentan mitigar esta disminución, sin embargo, en estos programas no conocen la proporción de sexos que van a ser devueltos al río. Este estudio busca determinar la proporción de sexos en neonatos de P. unifilis, mediante métodos morfométricos como una técnica alternativa a procedimientos invasivos de determinación sexual.Se registró un promedio de 31.1 huevos por nido, con un 70 % de éxito de eclosión y períodos de incubación de 72-83 días. El análisis histológico gonadal de 35 individuos permitió la clasificación de 14 neonatos machos y 21 neonatos hembras. El resultado del PCA, realizado con las medidas morfométricas de neonatos, mostró una tendencia en la separación de machos y hembras, con el largo, ancho, plastrón del caparazón como las medidas que más aportaron con esta tendencia, y un porcentaje de clasificación del 77.8 %. Sin embargo no se encontró una diferencia estadísticamente significativa (p <0.05) de las medidas morfométricas con respecto a la separación de sexos.

Aspects of the biology of the Antarctic dragonfish Gerlachea australis (Notothenioidei: Bathydraconidae) in the Weddell Sea, Antarctica

The Antarctic dragonfish Gerlachea australis is one of the most common bathydraconid species within the fish community of the Filchner Depression in the Weddell Sea. Nevertheless, several biological aspects of this species remain poorly known. The aim of this study was to provide new data on its population structure in terms of size, sex and age through sagittal otolith readings, as well as some reproductive traits based on macroscopic and histological analyses of gonads. The sex ratio in the sampled population was 1:1, with males being significantly smaller than females. Both sexes attained maximum age estimates of 14 years. Based on a von Bertalanffy growth model, females showed a higher asymptotic length than males at a comparable growth rate, thus reaching a higher growth performance. The spawning season was spread over a relatively long period, lasting at least from late December through late February. The reproductive effort in terms of fecundity and egg size diameter was similar to that of other bathydraconids, ranging from 739 to 1260 eggs/female and 3.2 mm after hydration, respectively. The fish size at first spawning (TL50) was 18.5 and 22.5 cm in males and females, corresponding to 80% of their maximum size. G. australis exhibited a combination of life history traits found in other high-Antarctic notothenioids, such as long gametogenesis, large eggs associated with low fecundity, relatively rapid body growth until reaching a delayed sexual maturity, moderate longevity and maximum size, and overall low growth performance.

Determination of a new index of sexual maturity (ISM) in zebra mussel using flow cytometry: interest in ecotoxicology.

The global dynamic spread of chemical contamination through the aquatic environment calls for the development of biomarkers of interest. Reproduction is a key element to be considered because it is related to the sustainability of species. Spermatogenesis is a complex process that leads to the formation of mature germ cells, whose steps and impairments need to be finely described in ecotoxicological analyses. The physiological process has been commonly described by histological analyses of gonads in different taxa. In the present paper, we describe the development of a novel technique to characterize spermatogenesis based on the analysis of the DNA content of germ cells by flow cytometry, using a DNA-intercalating agent. This new biomarker, referred to as an index of sexual maturity, proved relevant to describe the seasonal reproductive cycle of the zebra mussel, Dreissena polymorpha (Pallas, 1771), used as a sentinel species in the biomonitoring of continental waters and sensitive to highlight the reprotoxicity of carbamazepine (an anti-epileptic pharmaceutical) tested under ecosystemic conditions (mesocosms).

Histological profiling of gonads depicting protandrous hermaphroditism in Eleutheronema tetradactylum.

The fourfinger threadfin Eleutheronema tetradactylum is reported as a protandrous hermaphrodite from Australian waters, while being a gonochorist in reports from Singapore and India, with a single report of protandrous hermaphroditism from the latter. Histological analysis of gonads of fish from Indian waters confirms protandrous hermaphroditism in E. tetradactylum. The study was based on 480 fish examined from eight locations along the Indian coast. Mean total length (LT ) of male fish was 240 mm with the transition to female starting from 280 mm LT . Specimens confirmed as mature females were >380 mm LT .

Temporal Variation in Shell Growth Rate of CockleAnadara granosain Relation with its Reproductive Cycle

A study was conducted on the relationship between the reproductive cycle and shell growth rate of Anadara granosa (Linnaeus, 1758). Gonadal maturity stages, increment width, and environmental factors were examined by means of a field enclosure experiment in Balik Pulau, Penang Island, Malaysia, from December 2011 to November 2012. Histological analysis of gonads showed that gametogenic activity of A. granosa occurred throughout the year, with maximum spawning activity observed from April 2012 to late June 2012 (15%–28%) in males and from March 2012 to late June 2012 (19%–44%) in females. Shell cross-section analysis showed that the increment widths of both sexes in the growing group (indeterminate and developing stages) and the spawning group (ripe and spawning stages) ranged from 35–57 to 8–17 µm, respectively. Seawater temperature and salinity recorded on a daily basis throughout the study period ranged from 22–33°C and 29–31, respectively. A comparison of increment width and gonad development stages in different environmental conditions showed that shell growth in the growing group decreased when seawater temperature and salinity decreased slightly. In contrast, increment widths in the spawning group were much narrower and were influenced by energy consumption during ripe and spawning stages. This study shows spawning breaks in shell structure are considered markers for identifying the period of sexual maturity. Therefore, spawning breaks are suitable proxies for interpretation of the temporal changes in shell microgrowth lines in terms of reproductive cycle of cockle and understanding the number of spawning periods throughout the year.

Maternal contribution to spawning and early life-history strategies of the genus Lepidonotothen (Nototheniidae, Perciformes) along the southern Scotia Arc

The coastal fish community of the southern Scotia Arc, including the South Shetland Islands and the Bransfield Strait, is composed of the genus Lepidonotothen, which consists of three widely overlapping species such as L. kempi, L. larseni and L. nudifrons. The life-history strategies of these species driven by environmental and inter-specific interactions remain poorly known. In this paper, we estimate the maternal contribution to spawning of adult females in terms of fecundity and egg size through macroscopic and histological analyses of gonads. We further investigate the size and timing of hatching, growth rate and duration of the larval stage through microstructure analysis of sagittal otoliths collected from larval samples. All three species produced eggs of relatively small size at hatching, showing a trade-off between egg size and fecundity. Total fecundity was positively related to fish size during growth, as well as to maximum size. Female gonad investment was comparable among the species, as they all start spawning at about 65% of their maximum size with a similar gonadosomatic index. All species generated small larvae (altricial) which hatched over widely different periods, resulting in a temporal succession of larval occurrence. Compared to L. kempi, the other two species had relatively slow-growing larvae. Only L. kempi and L. larseni produced overwintering larvae. Differences in maternal contribution to spawning and early life-history traits of these species contribute to reduce interspecific competition for food through ecological niche partitioning.

Reproductive biology of the sand dollar, Peronella lesueuri (L. Agassiz, 1841) (Echinoidea: Clypeasteroida: Laganidae), in south-western Australia

The reproductive biology of the sand dollar Peronella lesueuri was studied between 2009 and 2011 in Cockburn Sound, a large coastal embayment in south-western Australia. Individuals of P. lesueuri did not display sexual size-dimorphism, and the population was found to have a sex ratio of 1:1. Maturity occurred over the range of 80–115 mm with all sand dollars larger than 115 mm having distinct gonads. Monthly histological analysis of gonads and changes in oocyte proportions over time indicated that P. lesueuri has an annual reproductive cycle; gametogenesis occurs in spring and spawning in summer. Differences in the rate of gametogenesis between 2009/2010 and 2010/2011 may have been influenced by higher temperatures experienced in 2010/2011. P. lesueuri have large ova (mean = 210 μm), which suggests the species has lecithotrophic larval development.

Reproductive resilience of ice‐dependent Antarctic silverfish in a rapidly changing system along the Western Antarctic Peninsula

AbstractThe Western Antarctic Peninsula (wAP) is globally one of the systems most heavily impacted by climate change, notably steep declines in sea ice extent. In forage species, reproductive resilience to change is particularly important because population fluctuations are rapidly communicated through the system via trophic interactions. The reproductive traits of the ice‐dependent forage species Antarctic silverfish (Pleuragramma antarctica) from different areas along the wAP and at the tip of the Antarctic Peninsula were investigated through macroscopic and histological analyses of gonads, with the aim to assess its reproductive potential and to test for spatial differences in fecundity and spawning season. Fish samples were collected in late summer off Charcot Island, in Marguerite Bay and off Joinville Island; no fish were caught in the central wAP. Samples from Charcot Island and Marguerite Bay consisted of adults in developing gonad stage, whereas those from Joinville consisted almost exclusively of juveniles. Mean GSI was relatively low (2–3%) and similar in both sexes, as specimens were still far from being actively reproducing. Developing females exhibited two discrete, though partially overlapping modes of oocytes of different size, with vitellogenic oocytes measuring 0.5–1.0 mm. Absolute and relative fecundity ranged between 3000 and 12,000 eggs per female and between 80 and 190 eggs·g−1, with a strong relationship between absolute fecundity and body size. These results were consistent with a single population at Charcot Island and Marguerite Bay and indicated substantial reproductive potential, which may mitigate population isolation and reductions in habitat availability but cannot ultimately offset catastrophic loss of spawning habitat linked to sea‐ice retreat.

INDUCED FUCTIONAL MALE OF CORAL TROUT GROUPER (Plectropomus leopardus) USING 17α-METHYLTESTOSTERONE HORMONE

The success of grouper seeds production is depends on the availability of qualified broodstock. The nature of grouper is protogynous hermaphrodite, causing difficulties to mantain female and a bit difficult to get male broodstock, one possibility to accelerate sex revers is by hormone manipulation. The aim of this experiment was to find effectiveness of 17α-methyl testosterone hormone to produce coral trout grouper (Plectropomus leopardus) functional male. The experiment was conducted in floating net cage by using 6 net cages with size of 2 m x 2 m x 2 m at density of 25 fish/cage, size of fish were 377.27±21.49 g. The fishes were treated by hormone implantation at concentration of 50 μg/kg body weight and without hormone implantation as a control with 3 replicates. The results showed that the highest concentration of testosteron in fish blood (1.144±0.135 pg/mL) was detected after four months of hormone treatment, but the concentration of testosteron in fish blood declined after 8th months of treatment. The treated fish with hormone grew faster than control. Based on histological analysis of gonad, female gonado somatic index was higher for treated fish compare to control. Its seems that hormone tratment lead to promote development of female maturity and than sex reverse into male become faster.

Reproductive aspects of the velvet belly lantern shark Etmopterus spinax (Condrichthyes: Etmopteridae), from the central western Mediterranean sea. Notes on gametogenesis and oviducal gland microstructure.

In this paper, the reproductive biology of the velvet belly lanternshark Etmopterus spinax was analyzed in Sardinian waters (central western Mediterranean). This species was sexually dimorphic with females growing to a larger size than males. Marked sexual dimorphism in size was also observed along the vertical gradient. Histological analysis of gonads was very useful in assigning macroscopical maturity stages. The investigation on the microstructure of oviducal gland (OG) highlighted four morphofunctional zones with mucous and/or proteic secretions according to the zone and to their specific functions and development. Sperm in the OG was found for the first time in E. spinax. The localization of sperm storage tubules deeper in OG suggested long-term sperm storage, which is in agreement with the long reproductive cycle described. This species matured late, specifically at 80.7% and 79% at the maximum observed size for females and males respectively. Mature specimens were found throughout the year with pregnant females observed in winter and autumn. A low fecundity was observed with a mean ovarian fecundity of 16.5 mature follicles.

Study of sex determination system in ship sturgeon, Acipenser nudiventris using meiotic gynogenesis

The sex ratios and sex determination mechanism of gynogenetic diploids of ship sturgeon, Acipenser nudiventris, have been investigated to verify the possibilities of sex control by chromosome manipulation in this species. Meiotic gynogenesis was induced in a female ship sturgeon using cold shock after egg activation with UV-irradiated sperm of a male Siberian sturgeon. Microsatellite DNA analysis was applied for verification of uniparental inheritance in the gynogenetic diploid group of fish. All the analyzed gynogenetic diploids possessed only maternal genotype in the examined experimental group of fish. In this study, a minimum of two distinctly selected diagnostic loci in the offspring was used to confirm exclusively maternal contribution. Also, these fish were analyzed for sex diagnostic. Histological analysis of gonads from gynogenetic diploids, obtained from one family, showed 73.3 % of females and 27.7 % of males. The observed sex ratio has suggested that the ship sturgeon have a female heterogametic sex determination system. Gynogenesis in this species with female heterogametic sex determination system will have important role in breeding program and reclamation of its natural population to produce both female and male progeny, while this species has been introduced in the red list of IUCN (International Union for Conservation of Nature and Natural Resources).

Reproductive cycle of the winged pearl oyster, Pteria penguin (Röding 1793) (Pteriidae) in north-eastern Australia

The spawning cycle of the winged pearl oyster, Pteria penguin, was studied at Orpheus Island, north-eastern Queensland to observe seasonal changes in gonad development, mean oocyte diameter and sex ratio over time. A total of 201 oysters were collected over 10 sampling periods, approximately every 5–6 weeks (mean = 20 oysters/sample). Histological analysis of gonads showed that spawning activity occurred mainly through the austral mid-spring to late summer (November to March), when mean monthly water temperature ranged between 27.5°C and 29.4°C. There was a primary spawning peak at the beginning of the spawning season in December, followed by a secondary peak in March. Mean oocyte diameter (µm) was highest during the warmer months, ranging from 31.2 ± 2.4 in November to 36.2 ± 3.2 in March, and sex ratio analysis showed the percentage of females in the population also peaked between 30% and 50% during this period.

Interannual variability of the reproductive strategy of the Peruvian anchovy off northern-central Peru

In this paper we analyze the standardized monthly anomalies of time series of the gonadosomatic index (GSI, 1986–2008), spawning fraction (SF, estimated by histological analysis of gonads, 1992–2008), and condition factor (1986–2008) of the Peruvian anchovy Engraulis ringens. Statistical analysis using filters showed, according to their mode of variability, the existence of three distinct periods for GSI (1986–1989, 1990–2000, and 2001–2008) and two for SF (1995–2001 and 2002–2008). Based on this, we built monthly GSI and SF patterns for each period, which showed marked and prolonged seasonal reproductive activity. The patterns found have been interpreted as changes in reproductive strategy. The condition factor showed no significant differences throughout the study period. We discuss changes in these periods and their implications for fisheries management measures.

Early sex identification in cultured beluga (Huso huso) using plasma steroid hormones

This study is aimed at evaluating when sex could be determined in beluga by examining levels of plasma steroids. Blood was taken from beluga from two stations (Shahid Rajaee: SR, Sari farm: SI) which were kept at 19°C at the age of 24 and 36 months and plasma testosterone (T), 11-ketotestosterone (KT) and estradiol (E2) concentrations and plasma calcium were determined. The results revealed that, plasma T and KT levels were significantly higher in males than females in both stations at the age of 24 and 36 months (P<0.05). There were no differences in E2 and calcium concentrations between males and females at both ages. In addition, the results showed that, plasma T increased significantly in both locations, with increasing age from 24 to 36 months. Histological analysis of gonads revealed that all but six of the SI farm fish at the age of 24 months had well differentiated testes with spermatogonia undergoing mitosis in cysts (Stage 2). The six of the population in SI farm, which had no differentiated gonad, had also the lowest weight in comparison to differentiated fish. It also appears that proliferation of spermatogonia is necessary for production of androgens and growth rate is influenced by water temperature. The results of this study revealed that, plasma T and KT can be used as good markers to determine the sex in the early life stage of beluga. Key words: Sturgeon, cultured beluga, sex determination, sex steroids.

Classes de comprimento e proporção sexual em Diplodon expansus (Mollusca, Bivalvia, Hyriidae) no rio Piraquara, Paraná, Brasil

O presente estudo tem como objetivo analisar a distribuição de classes de tamanho e proporção sexual ampliando o conhecimento do comportamento reprodutivo de Diplodon expansus (Küster, 1856) e da biodiversidade dos corpos de água da Área de Proteção Ambiental do Piraquara, Paraná, Brasil. A área de estudo corresponde a um trecho do rio Piraquara de águas lóticas, e mata ciliar relativamente bem preservada. Foram realizadas quatro coletas no período de março de 2006 a dezembro de 2006. No rio Piraquara o D. expansus ocorre em substratos arenoso e lodoso. O comprimento dos exemplares variou entre 17 mm e 65 mm, sendo que a maior frequência de classes de comprimento foi registrada para as classes intermediárias. A análise histológica das gônadas possibilitou a determinação de uma razão sexual 1:1, não tendo sido identificado nenhum exemplar hermafrodita, caracterizando uma população tipicamente dióica. Análises qualitativas e quantitativas demonstram uma gametogênese contínua, com picos de liberação larval no verão.

Diferentes granulometrias de rações sobre o ganho de peso, crescimento, sobrevivência e reversão sexual para tilápias-do-Nilo (Oreochromis niloticus)

O objetivo deste trabalho foi avaliar os efeitos de três diferentes granulometrias de rações fareladas (0,25, 0,35 e 0,50 mm) sobre o ganho de peso, crescimento, sobrevivência e proporção sexual para larvas de tilápia-do-Nilo (Oreochromis niloticus) aos 30, 60 e 90 dias de idade. Nos primeiros 30 dias de vida, as larvas foram revertidas com rações contendo hormônio 17 α-metiltestosterona na dosagem de 60 mg/kg de ração, respeitando-se as diferentes granulometrias e após este período, foram medidas, pesadas e contadas para cálculo da taxa de sobrevivência. Para as variáveis biométricas de peso e comprimento total, foi utilizado o delineamento inteiramente casualizado (DIC), em parcelas subdivididas, com três tratamentos e três repetições, considerando-se parcelas as três granulometrias de ração e subparcelas as três idades. Ao término do estudo, os peixes alimentados com as granulometrias 0,35 e 0,25 mm, obtiveram os melhores resultados para o ganho de peso (14,42 g e 13,36 g) e comprimento total (83,13 mm e 82,72 mm), não diferindo estatisticamente e as rações com diâmetros de grão 0,50 e 0,35 mm resultaram em 96,66% e 93,33% de machos, respectivamente, após análise histológica das gônadas, sem diferenças estatísticas entre os tratamentos.

Cytomorphology of female and male gonads in Antarctic toothfish Dissosctichus mawsoni (Nototheniidae) from the Ross Sea in the summer period

Results of histological analysis of gonads of female and male Antarctic toothfish Dissostichus mawsoni caught in the Ross Sea of the Pacific sector in the period of Antarctic summer (December–February) 2004–2005 are presented. Morphological indices and index of gonad maturity are described and ecological criteria of assessment of maturity stages of ovaries, cytological indices of oocytes, and the type of toothfish oogenesis are determined. It was established that in the period of fishing Antarctic toothfish, females and males with gonads at maturity stage III dominate. Ovaries contain two groups of oocytes of the period of trophoplasmatic growth and large oocytes of the nearest spawning season that comprise the smallest proportion of total sex cells. In the testes of two male toothfish, the primary fusion of renal and generative tissues was revealed. It is suggested that the termination of gonad maturity of toothfish takes place from March to April, and spawning takes place from June to August.

Meiotic gynogenesis revealed not homogametic female sex determination system in Siberian sturgeon ( Acipenser baeri Brandt)

Meiotic gynogenesis was induced in a Siberian sturgeon ( Acipenser baeri Brandt) by heat shock after egg activation with UV-irradiated sperm of a hybrid Siberian sturgeon × Russian sturgeon ( Acipenser gueldenstaedti Brandt). Microsatellite DNA analysis was applied for verification of unipaternal inheritance in the gynogenetic diploid group of fish. All the analyzed gynogenetic diploids possessed only maternal genotype in the examined experimental group of fish. Histological analysis of gonads of 50 gynogenetic diploids, obtained from one family, showed 81% of females and 19% of males. The observed sex ratio suggested that the Siberian sturgeon does not have a female homogametic sex determination system.

High doses of atrazine do not disrupt activity and expression of aromatase in female gonads of juvenile goldfish (Carassius auratus L.)

Juveniles female goldfish were exposed to atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine) at high doses, 100 and 1000 microg l(-1) during 56 days in order to evaluate the potential action of the herbicide as an endocrine disruptor. Plasma concentration of estradiol (E2) and 11-ketotestosterone (11-KT) as well as activity and expression of aromatase in the gonads were evaluated. These parameters were completed with morphological measures such as gonadosomatic index (GSI) and histological analyses of gonads. Morphological parameters at both 100 and 1000 microg l(-1) did not show any significant differences with the control groups. Correlated to the pathway hypothesized, no time-, dose-related effects were detected on the aromatase activity and the expression in the gonads of juvenile female goldfish. The same conclusion was attributed regarding the circulating E2 where no perceptible variation was detected. Nevertheless, a hormonal imbalance was detected for plasma concentration of the sex steroid 11-KT of fish exposed to 1000 microg l(-1) after 56 days exposure. In these particular experimental conditions, we failed to demonstrate an effect of atrazine through the induction of aromatase and hormonal imbalance associated.

REPRODUCTION OF THE BLUE LOBSTER PANULIRUS INFLATUS (BOUVIER, 1895) AT “BAHÍA DE LORETO” NATIONAL PARK, GULF OF CALIFORNIA

The reproductive season and first-maturity size of the blue lobster Panulirus inflatus were determined at the “Bahía de Loreto” National Park, Gulf of California. Two hundred fifty-six females were analyzed, finding that the onset of gamete development took place in February. The incubation season started in April and ended in November. The highest percentage of ovigerous females was observed in October (88.9%). Histological analysis of gonads revealed two peaks of gonad maturity, in May (75%) and August (75%). Temperature was positively correlated to the percent ovigerous females (rs = 0.85, P < 0.05) and with the percent ripe females (rs = 0.73, P < 0.05). The individual first-maturity size was 49.5 mm CL, whereas at a population level it was 80 mm CL, this being proposed as the minimum fishing size. The incubation period was estimated at 2–3 wk, and the histological evidence suggests that each female may spawn more than once and may undergo more than one incubation period during the reproductive season. The reproduction pattern at the Bahía de Loreto National Park in the Gulf of California is discontinuous, likely because the environmental conditions in this zone are more variable than in tropical regions. This feature should be taken into account by the Mexican government when regulating the exploitation of this resource in the study area.