Considerando o status atual de conhecimento da morfogenese e diferenciacao gonadal nos Teleostei ... more Considerando o status atual de conhecimento da morfogenese e diferenciacao gonadal nos Teleostei frente a restricao de informacoes, especialmente em aspectos tangentes ao estabelecimento do epitelio germinativo e sua relacao com a formacao da estrutura gonadal tomou-se aqui como modelos biologicos Tanichthys albonubes, Gymnocorymbus ternetzi, Corydoras schwartzi, Amatitlania nigrofasciata e Poecilia reticulata, representando as series Otophysi, Percomorpha e Atherinomorpha, visando estabelecer uma analise comparativa da diferenciacao gonadal entre as especies, considerando suas posicoes na escala filogenetica. A proliferacao e diferenciacao de celulas germinativas e somaticas a partir do primordio gonadal em T. albonubes, G. ternetzi, C. schwartzi, A. nigrofasciata e P. reticulata levam a formacao das diferentes estruturas ovarianas e testiculares e a constituicao do epitelio germinativo que margeia as lamelas ovigeras e os tubulos/lobulos testiculares. Nesses animais, o primordio gonadal e formado por celulas germinativas primordiais (CGPs) rodeadas por celulas somaticas. Apos sucessivas divisoes mitoticas das celulas somaticas, o tecido gonadal aumenta, originando uma gonada indiferenciada, com as mesmas caracteristicas morfologicas entre machos e femeas de T. albonubes e C. schwartzi. Em A. nigrofasciata e P. reticulata grupos de celulas germinativas e somaticas organizam-se de maneira distintas em machos e femeas. Nas gonadas femininas, as CGPs estao distribuidas por todo o tecido gonadal, enquanto que nas masculinas, as CGPs localizam-se na periferia. Na regiao dorsal das gonadas masculinas de A. nigrofasciata e P. reticulata, celulas somaticas organizam-se formando o ducto testicular, enquanto que em T. albonubes, G. ternetzi e C. schwartzi esse e a ultima estrutura a se formar. Nas gonadas femininas das cinco especies, os processos envolvidos na diferenciacao gonadal, como a foliculogenese, o estabelecimento do epitelio germinativo e a formacao da cavidade ovariana sao bastante semelhantes. Nas gonadas masculinas, as celulas somaticas, pre-Sertoli, associam-se as CGPs, formando cistos de espermatogonias; estas proliferam formando conjuntos celulares. Em T. albonubes e A. nigrofasciata os cistos de espermatogonias que constituem um mesmo conjunto, afastam-se uns dos outros, criando um espaco central, que se torna maior, originando um compartimento luminal, delimitado por cistos de espermatogonias. Formam-se os tubulos e lobulos testiculares e o epitelio 2 germinativo masculino e estabelecido. Em G. ternetzi o tecido gonadal masculino e estabelecido e organizado em tubulos apos a diferenciacao gonadal feminina, sobre um ovario previamente desenvolvido, constituindo uma diferenciacao gonocoristica do tipo indireta. C. schwartzi apresenta um tecido gonadal masculino compacto, que sofre degeneracoes no interior de estruturas acinares compostas por cistos, para constituir os tubulos testiculares. Em P. reticulata, os conjuntos de espermatogonias conectam-se ao ducto em formacao, originando os primeiros lobulos testiculares. Ao final da diferenciacao gonadal, os testiculos de T. albonubes, G. ternetzi e C. schwartzi apresentam espermatogonias distribuidas aleatoriamente no tubulo. Estes anastomosam-se, caracterizando o testiculo como tubular anastomosado. Em P. reticulata, as espermatogonias ficam restritas na regiao periferica dos lobulos, os quais nao apresentam lumen testicular, caracteristicas estas de um testiculo lobular restrito. A mesma distribuicao aleatoria de cistos nos tubulos dos Otophysi ocorre nos lobulos testiculares de A. nigrofasciata, caracterizando um testiculo com organizacao lobular do tipo irrestrita. Abstract
Marine aquaculture has grown worldwide in recent decades, but around 90% of ornamental marine fis... more Marine aquaculture has grown worldwide in recent decades, but around 90% of ornamental marine fish available in aquarium are results of extractive practices. Ornamental fish farming try to supply the indiscriminate collection of native fish, avoiding their extinction. However, marine fish breeding in captivity still walks on a small scale, being an activity dependent on the acclimatization of the species in tanks, ability of the breeder to produce viable eggs, acquisition of large quantities of larvae, and maintaining the juveniles until they become young adults. The cost of the activity is usually quite high, making it difficult for small producers to invest. The possibility of developing new methodologies could help in reducing the maintenance value of aquaria, ensuring a fish breeding at a lower cost than usual. Thus, using three species of clownfish, we intend to disseminate experiences acquired in the reproduction of these species, at a low cost and with great economic viabilit...
Original article Immunostaining through immunohistochemical or immunofluorescence techniques has ... more Original article Immunostaining through immunohistochemical or immunofluorescence techniques has been widely used in recent years as a result of the increasing availability of antibodies. The identification of specific epitopes in biological tissue by antigen-antibody reactions, detected by a visual marker, that allows their identification under microscopy, provides more accurate diagnoses. Today, the most commonly used methods in immunohistochemistry refer to histological sections obtained from paraffin sections, cryostat or cell suspensions. However, these methodologies are not always suitable, especially for small samples. Thus, in order to perform immunostaining in difficult to manipulate biological tissues, in totum immunohistochemical processing was performed in embryos, larvae and total biological tissues of fishes. The development of this technique was adapted from proposed protocols for free-floating immunohistochemistry. The in totum biological samples immersed in different types of fixing solutions and washed in Sorensen Phosphate Buffer. Next, endogenous peroxidase was blocked. The antigen recovery was performed, followed by the nonspecific blockade and incubation with different primary antibodies. Subsequently, the in totum samples were incubated with different biotinylated secondary antibodies and stained with DAB-H2O2. The material was washed in distilled water and fixed again. Fluorescent secondary antibodies were also used in other similar samples, following the same initial protocol. The samples were submitted to historesin embeding and the histological sections (5µm thick) were obtained in microtome. DAB stained immunohistochemistry slides were counterstained with Hematoxylin. Samples fluorophore labeled were imunolabeling with DAPI. The immunostaining in both immunohistochemistry and immunofluorescence was maintained throughout historesin processing. The historesin embedding allows a better preservation of biological tissues and obtaining thinner histological sections that paraffin or frozen material. Consequently, the image resolution is potentially improved. In this regard, this work becomes an important toll to be used in immunohistochemical techniques, giving better results in tissues that are difficult to process in paraffin or freezing.
SummaryChaetodon striatus is a cosmopolitan seawater species present in aquaria all over the worl... more SummaryChaetodon striatus is a cosmopolitan seawater species present in aquaria all over the world and its extractivism is quite high. The lack of studies on the reproductive biology of C. striatus contributes to the difficulty in managing the species outside its natural habitat. Without knowledge of the mechanisms that control or affect gonadal changes, reproduction of C. striatus in captivity has become almost impossible, considering that the species is quite sensitive and the effect of captive conditions on its reproductive biology is unknown. Therefore, this study aimed to evaluate the effect on its reproductive biology of the animal’s confinement and possible alteration in structure of the ovaries. In C. striatus, after oocyte development, for animals confined in small spaces, maturing oocytes undergo atresia. During atresia, ovarian follicles were at different stages of degeneration, characterized by the progressive loss of the basement membrane and disorganization of the foll...
Numa nova visao da morfogenese gonadal, sua descricao em Cyprinus carpio, mostra como a prolifera... more Numa nova visao da morfogenese gonadal, sua descricao em Cyprinus carpio, mostra como a proliferacao e diferenciacao de celulas germinativas e somaticas a partir do primordio gonadal levam a formacao das diferentes estruturas ovarianas e testiculares e a constituicao do epitelio germinativo que margeia as lamelas ovigeras e os tubulos testiculares. Em C. carpio, o primordio gonadal e formado por celulas germinativas primordiais (CGPs) rodeadas por celulas somaticas. Apos sucessivas divisoes mitoticas das celulas somaticas, o tecido gonadal aumenta em comprimento e espessura. As CGPs isoladas entre celulas somaticas se dividem mitoticamente formando grupos de celulas germinativas, que se organizam em cordoes continuos, os quais sao invadidos por celulas somaticas, levando a uma reorganizacao estrutural e diferenciacao gonadal. Nas gonadas femininas, as oogonias sao envolvidas por expansoes citoplasmaticas das agora celulas pre-foliculares, formando cistos, delimitados por uma membrana basal em formacao. Cada oogonia divide-se por mitose, formando novas oogonias ou entra em meiose originando os oocitos. Com a entrada e permanencia em diploteno, os oocitos, ainda no interior dos cistos, iniciam seu desenvolvimento que completar-se-a no interior dos foliculos ovarianos. As celulas pre-foliculares progressivamente interpenetram nos cistos e envolvem cada oocito individualizando-os. Estas gradativamente sintetizam a membrana basal envolvendo progressivamente o foliculo em formacao. As celulas foliculares assentadas em parte na membrana basal do proprio epitelio germinativo mantem uma regiao de contato entre o foliculo ovariano e o epitelio germinativo, que compartilham uma mesma membrana basal. Ao termino da foliculogenese, o oocito inicia seu crescimento primario. No tecido gonadal, celulas mesenquimais se interconectam e se diferenciam, dando origem ao estroma ovariano, isolado do compartimento germinativo pela membrana basal. Celulas indiferenciadas do estroma emitem prolongamentos que contatam os foliculos em formacao, constituindo a teca. Celulas somaticas perifericas por migracao e invaginacao no tecido gonadal, formam as lamelas ovigeras. Lâminas teciduais de celulas somaticas formam-se em ambos os lados do ovario, projetando-se ate se contatarem, formando o lumen ovariano. Nas gonadas masculinas, as celulas somaticas, pre- Sertoli, invadem os cordoes continuos de CGPs. Estas, agora espermatogonias, sao envolvidas por expansoes citoplasmaticas das celulas de Sertoli, formando cistos. Estes formam conjuntos celulares que se distribuem ao longo da gonada, cada qual circundado por celulas somaticas. Ao redor de cada conjunto celular, inicia-se a formacao da membrana basal, porem de forma incompleta. Gradativamente, os cistos de espermatogonias que constituem um mesmo conjunto, afastam-se uns dos outros, criando um espaco central. Celulas somaticas de conjuntos celulares adjacentes afastam-se, permitindo fusao entre os dois conjuntos celulares e aumento do espaco central formando um unico compartimento luminal, delimitado por cistos de espermatogonias, estes, apoiados na membrana basal. Formam-se os tubulos testiculares e o epitelio germinativo masculino e estabelecido. O compartimento germinativo encontra-se agora separado pela membrana basal dos demais componentes celulares, que irao se diferenciar no compartimento intersticial. Inicia-se a espermatogenese no interior de cada cisto, de forma sincronica. Apos espermiogenese, os espermatozoides sao liberados no lumen, e os tubulos testiculares se anastomosam, culminando com a formacao do ducto espermatico na porcao dorsal do testiculo. Abstract
Most teleosts are externally fertilizing, with internal fertilization occurring as a relatively r... more Most teleosts are externally fertilizing, with internal fertilization occurring as a relatively rare event. Until now, Euteleosteomorpha is the only teleost cohort known to undergo internal fertilization. In the teleost cohort Otomorpha, it has been recorded the presence of sperm in the ovaries of some species of Characiformes and Siluriformes, but no fertilized eggs have been found so far in the female reproductive tract. It has been presumed that oocytes can be released into the water with associated spermatozoa and only there becomes fertilized, and the term insemination has been used to characterize the strategy adopted by these fish. Here, we present the discovery of the first case of internal fertilization in the teleost cohort Otomorpha, in Compsura heterura (Characiformes: Characidae). In the course of spawning, the eggs form the perivitelline space and the animal and vegetative poles within the ovaries, evidencing oocyte fertilization. The newly spawned eggs then continue t...
In most Teleostei fish, the gametogenesis is a cyclical and seasonal event. The renewal of gamete... more In most Teleostei fish, the gametogenesis is a cyclical and seasonal event. The renewal of gametes, through their differentiation, development, maturation and release causes several changes in the morphological characteristics of the ovaries and testes throughout the annual reproductive cycles. These alterations are used to recognize different phases in the reproductive cycles. However, as the number of studies of fish reproduction increased, the number of types of gonadal classification and nomenclatures also diversified. This may make it difficult to communication between researchers and the aquaculture activity, since the recognition of these phases is one of the most important parameters applied in the management of fishery resources. In addition, the terminologies proposed in most of the current studies refer to reproductive stages applicable to marine fish, with marked and defined seasonality characteristics. In this way, this report presents a recent proposal for the recognit...
Teleostei present great plasticity regarding sex change. During sex reversal, the whole gonad inc... more Teleostei present great plasticity regarding sex change. During sex reversal, the whole gonad including the germinal epithelium undergoes significant changes, remodeling, and neoformation. However, there is no information on the changes that occur within the interstitial compartment. Considering the lack of information, especially on the role played by metalloproteinases (MMPs) in fish gonadal remodeling, the aim of this study was to evaluate the action of MMPs on gonads of sex reversed females of , a fresh water protogynic diandric fish. Gonads were processed for light microscopy and blood samples were used for the determination of plasma sex steroid levels. During sex reversal, degeneration of the ovaries occurred and were gradually replaced by the germinal tissue of the male. The action of the MMPs induces significant changes in the interstitial compartment, allowing the reorganization of germinal epithelium. Leydig cells also showed an important role in female to male reversion....
The golden mussel Limnoperna fortunei is an invasive species that has quickly dispersed and colon... more The golden mussel Limnoperna fortunei is an invasive species that has quickly dispersed and colonized several potential different habitats distributed all over the world, causing environmental and economic impacts. The control of the species depends on knowledge of its reproductive aspects. Approximately 1 200 specimens of L. fortunei were sampled periodically on the upper Paraná River floodplain (Brazil) from March 2010 to December 2012. Thus, in order to contribute to a better understanding of the reproductive aspects of L. fortunei, using high resolution histology, we described the cellular dynamic of the male and female germinal epithelium during the annual reproductive life history of this species. Based on the activity of the germinal epithelium and consequent germ cell development, this study has resulted in the recognition of the following reproductive phases: Developing, Spawning Capable, Regressing and Regenerating. In the characterization of these phases the following ger...
Distinct types of oogonia are found in the germinal epithelium that borders the ovarian lamellae ... more Distinct types of oogonia are found in the germinal epithelium that borders the ovarian lamellae of Pimelodus maculatus: A-undifferentiated, A-differentiated and B-oogonia. This is similar to the situation observed for spermatogonia in the vertebrate testis. The single A-undifferentiated oogonia divide by mitosis giving rise to A-groups of single differentiated oogonia, each enclosed by epithelial cells that are prefollicle cells. Subsequently, the single A-differentiated oogonia proliferate to generate B-oogonia that are interconnected by cytoplasmic bridges, hence, forming germline cysts. The prefollicle cells associated with them also divide. Within the germline cysts, B-oogonia enter meiosis becoming oocytes. Meiotic prophase and early folliculogenesis occur within the germline cysts. During folliculogenesis, prefollicle cells grow between the oocytes, encompassing and individualizing each of them. The intercellular bridges disappear, and the germline cysts are broken down. Next, a basement membrane begins to form around the nascent follicle, separating an oocyte and its associated prefollicle cells from the cell nest. Folliculogenesis is completed when the oocyte and the now follicle cells are totally encompassed by a basement membrane. Cells derived from the ovarian stroma encompass the newly-formed ovarian follicle, and become the theca, thereby completing the formation of the follicle complex. Follicle complexes remain attached to the germinal epithelium as they share a portion of basement membrane. This attachment site is where the oocyte is released during ovulation. The postovulatory follicle complex is continuous with the germinal epithelium as both are supported by a continuous basement membrane. The findings in P. maculatus reinforce the hypothesis that ovarian follicle formation represents a conserved process throughout vertebrate evolution.
Considerando o status atual de conhecimento da morfogenese e diferenciacao gonadal nos Teleostei ... more Considerando o status atual de conhecimento da morfogenese e diferenciacao gonadal nos Teleostei frente a restricao de informacoes, especialmente em aspectos tangentes ao estabelecimento do epitelio germinativo e sua relacao com a formacao da estrutura gonadal tomou-se aqui como modelos biologicos Tanichthys albonubes, Gymnocorymbus ternetzi, Corydoras schwartzi, Amatitlania nigrofasciata e Poecilia reticulata, representando as series Otophysi, Percomorpha e Atherinomorpha, visando estabelecer uma analise comparativa da diferenciacao gonadal entre as especies, considerando suas posicoes na escala filogenetica. A proliferacao e diferenciacao de celulas germinativas e somaticas a partir do primordio gonadal em T. albonubes, G. ternetzi, C. schwartzi, A. nigrofasciata e P. reticulata levam a formacao das diferentes estruturas ovarianas e testiculares e a constituicao do epitelio germinativo que margeia as lamelas ovigeras e os tubulos/lobulos testiculares. Nesses animais, o primordio gonadal e formado por celulas germinativas primordiais (CGPs) rodeadas por celulas somaticas. Apos sucessivas divisoes mitoticas das celulas somaticas, o tecido gonadal aumenta, originando uma gonada indiferenciada, com as mesmas caracteristicas morfologicas entre machos e femeas de T. albonubes e C. schwartzi. Em A. nigrofasciata e P. reticulata grupos de celulas germinativas e somaticas organizam-se de maneira distintas em machos e femeas. Nas gonadas femininas, as CGPs estao distribuidas por todo o tecido gonadal, enquanto que nas masculinas, as CGPs localizam-se na periferia. Na regiao dorsal das gonadas masculinas de A. nigrofasciata e P. reticulata, celulas somaticas organizam-se formando o ducto testicular, enquanto que em T. albonubes, G. ternetzi e C. schwartzi esse e a ultima estrutura a se formar. Nas gonadas femininas das cinco especies, os processos envolvidos na diferenciacao gonadal, como a foliculogenese, o estabelecimento do epitelio germinativo e a formacao da cavidade ovariana sao bastante semelhantes. Nas gonadas masculinas, as celulas somaticas, pre-Sertoli, associam-se as CGPs, formando cistos de espermatogonias; estas proliferam formando conjuntos celulares. Em T. albonubes e A. nigrofasciata os cistos de espermatogonias que constituem um mesmo conjunto, afastam-se uns dos outros, criando um espaco central, que se torna maior, originando um compartimento luminal, delimitado por cistos de espermatogonias. Formam-se os tubulos e lobulos testiculares e o epitelio 2 germinativo masculino e estabelecido. Em G. ternetzi o tecido gonadal masculino e estabelecido e organizado em tubulos apos a diferenciacao gonadal feminina, sobre um ovario previamente desenvolvido, constituindo uma diferenciacao gonocoristica do tipo indireta. C. schwartzi apresenta um tecido gonadal masculino compacto, que sofre degeneracoes no interior de estruturas acinares compostas por cistos, para constituir os tubulos testiculares. Em P. reticulata, os conjuntos de espermatogonias conectam-se ao ducto em formacao, originando os primeiros lobulos testiculares. Ao final da diferenciacao gonadal, os testiculos de T. albonubes, G. ternetzi e C. schwartzi apresentam espermatogonias distribuidas aleatoriamente no tubulo. Estes anastomosam-se, caracterizando o testiculo como tubular anastomosado. Em P. reticulata, as espermatogonias ficam restritas na regiao periferica dos lobulos, os quais nao apresentam lumen testicular, caracteristicas estas de um testiculo lobular restrito. A mesma distribuicao aleatoria de cistos nos tubulos dos Otophysi ocorre nos lobulos testiculares de A. nigrofasciata, caracterizando um testiculo com organizacao lobular do tipo irrestrita. Abstract
Marine aquaculture has grown worldwide in recent decades, but around 90% of ornamental marine fis... more Marine aquaculture has grown worldwide in recent decades, but around 90% of ornamental marine fish available in aquarium are results of extractive practices. Ornamental fish farming try to supply the indiscriminate collection of native fish, avoiding their extinction. However, marine fish breeding in captivity still walks on a small scale, being an activity dependent on the acclimatization of the species in tanks, ability of the breeder to produce viable eggs, acquisition of large quantities of larvae, and maintaining the juveniles until they become young adults. The cost of the activity is usually quite high, making it difficult for small producers to invest. The possibility of developing new methodologies could help in reducing the maintenance value of aquaria, ensuring a fish breeding at a lower cost than usual. Thus, using three species of clownfish, we intend to disseminate experiences acquired in the reproduction of these species, at a low cost and with great economic viabilit...
Original article Immunostaining through immunohistochemical or immunofluorescence techniques has ... more Original article Immunostaining through immunohistochemical or immunofluorescence techniques has been widely used in recent years as a result of the increasing availability of antibodies. The identification of specific epitopes in biological tissue by antigen-antibody reactions, detected by a visual marker, that allows their identification under microscopy, provides more accurate diagnoses. Today, the most commonly used methods in immunohistochemistry refer to histological sections obtained from paraffin sections, cryostat or cell suspensions. However, these methodologies are not always suitable, especially for small samples. Thus, in order to perform immunostaining in difficult to manipulate biological tissues, in totum immunohistochemical processing was performed in embryos, larvae and total biological tissues of fishes. The development of this technique was adapted from proposed protocols for free-floating immunohistochemistry. The in totum biological samples immersed in different types of fixing solutions and washed in Sorensen Phosphate Buffer. Next, endogenous peroxidase was blocked. The antigen recovery was performed, followed by the nonspecific blockade and incubation with different primary antibodies. Subsequently, the in totum samples were incubated with different biotinylated secondary antibodies and stained with DAB-H2O2. The material was washed in distilled water and fixed again. Fluorescent secondary antibodies were also used in other similar samples, following the same initial protocol. The samples were submitted to historesin embeding and the histological sections (5µm thick) were obtained in microtome. DAB stained immunohistochemistry slides were counterstained with Hematoxylin. Samples fluorophore labeled were imunolabeling with DAPI. The immunostaining in both immunohistochemistry and immunofluorescence was maintained throughout historesin processing. The historesin embedding allows a better preservation of biological tissues and obtaining thinner histological sections that paraffin or frozen material. Consequently, the image resolution is potentially improved. In this regard, this work becomes an important toll to be used in immunohistochemical techniques, giving better results in tissues that are difficult to process in paraffin or freezing.
SummaryChaetodon striatus is a cosmopolitan seawater species present in aquaria all over the worl... more SummaryChaetodon striatus is a cosmopolitan seawater species present in aquaria all over the world and its extractivism is quite high. The lack of studies on the reproductive biology of C. striatus contributes to the difficulty in managing the species outside its natural habitat. Without knowledge of the mechanisms that control or affect gonadal changes, reproduction of C. striatus in captivity has become almost impossible, considering that the species is quite sensitive and the effect of captive conditions on its reproductive biology is unknown. Therefore, this study aimed to evaluate the effect on its reproductive biology of the animal’s confinement and possible alteration in structure of the ovaries. In C. striatus, after oocyte development, for animals confined in small spaces, maturing oocytes undergo atresia. During atresia, ovarian follicles were at different stages of degeneration, characterized by the progressive loss of the basement membrane and disorganization of the foll...
Numa nova visao da morfogenese gonadal, sua descricao em Cyprinus carpio, mostra como a prolifera... more Numa nova visao da morfogenese gonadal, sua descricao em Cyprinus carpio, mostra como a proliferacao e diferenciacao de celulas germinativas e somaticas a partir do primordio gonadal levam a formacao das diferentes estruturas ovarianas e testiculares e a constituicao do epitelio germinativo que margeia as lamelas ovigeras e os tubulos testiculares. Em C. carpio, o primordio gonadal e formado por celulas germinativas primordiais (CGPs) rodeadas por celulas somaticas. Apos sucessivas divisoes mitoticas das celulas somaticas, o tecido gonadal aumenta em comprimento e espessura. As CGPs isoladas entre celulas somaticas se dividem mitoticamente formando grupos de celulas germinativas, que se organizam em cordoes continuos, os quais sao invadidos por celulas somaticas, levando a uma reorganizacao estrutural e diferenciacao gonadal. Nas gonadas femininas, as oogonias sao envolvidas por expansoes citoplasmaticas das agora celulas pre-foliculares, formando cistos, delimitados por uma membrana basal em formacao. Cada oogonia divide-se por mitose, formando novas oogonias ou entra em meiose originando os oocitos. Com a entrada e permanencia em diploteno, os oocitos, ainda no interior dos cistos, iniciam seu desenvolvimento que completar-se-a no interior dos foliculos ovarianos. As celulas pre-foliculares progressivamente interpenetram nos cistos e envolvem cada oocito individualizando-os. Estas gradativamente sintetizam a membrana basal envolvendo progressivamente o foliculo em formacao. As celulas foliculares assentadas em parte na membrana basal do proprio epitelio germinativo mantem uma regiao de contato entre o foliculo ovariano e o epitelio germinativo, que compartilham uma mesma membrana basal. Ao termino da foliculogenese, o oocito inicia seu crescimento primario. No tecido gonadal, celulas mesenquimais se interconectam e se diferenciam, dando origem ao estroma ovariano, isolado do compartimento germinativo pela membrana basal. Celulas indiferenciadas do estroma emitem prolongamentos que contatam os foliculos em formacao, constituindo a teca. Celulas somaticas perifericas por migracao e invaginacao no tecido gonadal, formam as lamelas ovigeras. Lâminas teciduais de celulas somaticas formam-se em ambos os lados do ovario, projetando-se ate se contatarem, formando o lumen ovariano. Nas gonadas masculinas, as celulas somaticas, pre- Sertoli, invadem os cordoes continuos de CGPs. Estas, agora espermatogonias, sao envolvidas por expansoes citoplasmaticas das celulas de Sertoli, formando cistos. Estes formam conjuntos celulares que se distribuem ao longo da gonada, cada qual circundado por celulas somaticas. Ao redor de cada conjunto celular, inicia-se a formacao da membrana basal, porem de forma incompleta. Gradativamente, os cistos de espermatogonias que constituem um mesmo conjunto, afastam-se uns dos outros, criando um espaco central. Celulas somaticas de conjuntos celulares adjacentes afastam-se, permitindo fusao entre os dois conjuntos celulares e aumento do espaco central formando um unico compartimento luminal, delimitado por cistos de espermatogonias, estes, apoiados na membrana basal. Formam-se os tubulos testiculares e o epitelio germinativo masculino e estabelecido. O compartimento germinativo encontra-se agora separado pela membrana basal dos demais componentes celulares, que irao se diferenciar no compartimento intersticial. Inicia-se a espermatogenese no interior de cada cisto, de forma sincronica. Apos espermiogenese, os espermatozoides sao liberados no lumen, e os tubulos testiculares se anastomosam, culminando com a formacao do ducto espermatico na porcao dorsal do testiculo. Abstract
Most teleosts are externally fertilizing, with internal fertilization occurring as a relatively r... more Most teleosts are externally fertilizing, with internal fertilization occurring as a relatively rare event. Until now, Euteleosteomorpha is the only teleost cohort known to undergo internal fertilization. In the teleost cohort Otomorpha, it has been recorded the presence of sperm in the ovaries of some species of Characiformes and Siluriformes, but no fertilized eggs have been found so far in the female reproductive tract. It has been presumed that oocytes can be released into the water with associated spermatozoa and only there becomes fertilized, and the term insemination has been used to characterize the strategy adopted by these fish. Here, we present the discovery of the first case of internal fertilization in the teleost cohort Otomorpha, in Compsura heterura (Characiformes: Characidae). In the course of spawning, the eggs form the perivitelline space and the animal and vegetative poles within the ovaries, evidencing oocyte fertilization. The newly spawned eggs then continue t...
In most Teleostei fish, the gametogenesis is a cyclical and seasonal event. The renewal of gamete... more In most Teleostei fish, the gametogenesis is a cyclical and seasonal event. The renewal of gametes, through their differentiation, development, maturation and release causes several changes in the morphological characteristics of the ovaries and testes throughout the annual reproductive cycles. These alterations are used to recognize different phases in the reproductive cycles. However, as the number of studies of fish reproduction increased, the number of types of gonadal classification and nomenclatures also diversified. This may make it difficult to communication between researchers and the aquaculture activity, since the recognition of these phases is one of the most important parameters applied in the management of fishery resources. In addition, the terminologies proposed in most of the current studies refer to reproductive stages applicable to marine fish, with marked and defined seasonality characteristics. In this way, this report presents a recent proposal for the recognit...
Teleostei present great plasticity regarding sex change. During sex reversal, the whole gonad inc... more Teleostei present great plasticity regarding sex change. During sex reversal, the whole gonad including the germinal epithelium undergoes significant changes, remodeling, and neoformation. However, there is no information on the changes that occur within the interstitial compartment. Considering the lack of information, especially on the role played by metalloproteinases (MMPs) in fish gonadal remodeling, the aim of this study was to evaluate the action of MMPs on gonads of sex reversed females of , a fresh water protogynic diandric fish. Gonads were processed for light microscopy and blood samples were used for the determination of plasma sex steroid levels. During sex reversal, degeneration of the ovaries occurred and were gradually replaced by the germinal tissue of the male. The action of the MMPs induces significant changes in the interstitial compartment, allowing the reorganization of germinal epithelium. Leydig cells also showed an important role in female to male reversion....
The golden mussel Limnoperna fortunei is an invasive species that has quickly dispersed and colon... more The golden mussel Limnoperna fortunei is an invasive species that has quickly dispersed and colonized several potential different habitats distributed all over the world, causing environmental and economic impacts. The control of the species depends on knowledge of its reproductive aspects. Approximately 1 200 specimens of L. fortunei were sampled periodically on the upper Paraná River floodplain (Brazil) from March 2010 to December 2012. Thus, in order to contribute to a better understanding of the reproductive aspects of L. fortunei, using high resolution histology, we described the cellular dynamic of the male and female germinal epithelium during the annual reproductive life history of this species. Based on the activity of the germinal epithelium and consequent germ cell development, this study has resulted in the recognition of the following reproductive phases: Developing, Spawning Capable, Regressing and Regenerating. In the characterization of these phases the following ger...
Distinct types of oogonia are found in the germinal epithelium that borders the ovarian lamellae ... more Distinct types of oogonia are found in the germinal epithelium that borders the ovarian lamellae of Pimelodus maculatus: A-undifferentiated, A-differentiated and B-oogonia. This is similar to the situation observed for spermatogonia in the vertebrate testis. The single A-undifferentiated oogonia divide by mitosis giving rise to A-groups of single differentiated oogonia, each enclosed by epithelial cells that are prefollicle cells. Subsequently, the single A-differentiated oogonia proliferate to generate B-oogonia that are interconnected by cytoplasmic bridges, hence, forming germline cysts. The prefollicle cells associated with them also divide. Within the germline cysts, B-oogonia enter meiosis becoming oocytes. Meiotic prophase and early folliculogenesis occur within the germline cysts. During folliculogenesis, prefollicle cells grow between the oocytes, encompassing and individualizing each of them. The intercellular bridges disappear, and the germline cysts are broken down. Next, a basement membrane begins to form around the nascent follicle, separating an oocyte and its associated prefollicle cells from the cell nest. Folliculogenesis is completed when the oocyte and the now follicle cells are totally encompassed by a basement membrane. Cells derived from the ovarian stroma encompass the newly-formed ovarian follicle, and become the theca, thereby completing the formation of the follicle complex. Follicle complexes remain attached to the germinal epithelium as they share a portion of basement membrane. This attachment site is where the oocyte is released during ovulation. The postovulatory follicle complex is continuous with the germinal epithelium as both are supported by a continuous basement membrane. The findings in P. maculatus reinforce the hypothesis that ovarian follicle formation represents a conserved process throughout vertebrate evolution.
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Papers by Talita Sarah Mazzoni