Morfologia reprodutiva masculina e espermatogênese da raia de água doce Potamotrygon amandae (Myliobatiformes, Potamotrygonidae)
Data
2022-01-31
Autores
Delgado, Maria Luiza Ribeiro
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Com o enchimento do reservatório da Usina Hidrelétrica de Itaipu, rio Paraná, Brasil, a partir da década de 1970, o obstáculo natural que isolava parte da ictiofauna do Alto Rio Paraná da fauna dos sistemas à jusante deixou de existir, possibilitando a colonização por espécies invasoras, como a raia Potamotrygon amandae. Chondrichthyes (tubarões, raias e quimeras) apresentam o trato reprodutivo complexo, mais semelhante aos anfíbios e amniotas do que peixes teleósteos, formado por testículos, epidídimo, glândula de Leydig e vesícula seminal. Assim, é de grande importância analisar o funcionamento destes órgãos e seus respectivos papéis na reprodução. O trabalho objetivou descrever a morfologia macro e microscópica do trato reprodutivo masculino de Potamotrygon amandae, assim como a descrição da espermatogênese da espécie. Indivíduos machos de Potamotrygon amandae (n=10) foram coletados no reservatório de Jupiá, rio Paraná, Ilha Solteira-SP, anestesiados com solução de MS 222; os órgãos reprodutivos foram removidos, fragmentados e fixados em solução de paraformaldeído a 4% e glutaraldeído a 2% em tampão fosfato Sorensen, 0,1M a pH 7,2, e processados para análise em microscopia de luz. Em P. amandae os testículos são separados do restante dos órgãos do trato por uma camada fina de mesentério, exibem lóbulos testiculares e zonas germinativas bem demarcados. Os demais órgãos estão localizados próximos aos rins, na parte dorsal da cavidade celomática. O epidídimo, órgão alongado e avermelhado, tem a parte cranial avantajada, liga-se a glândula de Leydig pela extremidade caudal. As glândulas têm a porção cranial estreita, corpo avantajado, coloração avermelhada; sua porção caudal liga-se a vesícula seminal, órgão longo e curvilíneo, coloração hialina que se estende até a abertura da cloaca. O epidídimo é constituído por uma rede anastomosada de ramificações oriundas do ducto deferente formada por ductos e túbulos, ambos têm a função de transporte de espermatozoides e apresentam epitélio pseudoestratificado e estratificado colunar, respectivamente. A glândula é composta pelo ducto deferente e pelo tecido glandular que envolve o ducto. O tecido glandular é composto por unidades glandulares do tipo tubular ramificado, com epitélio simples colunar, células de núcleos basais e citoplasma apical, maioria secretora e é possível observar secreção no lúmen. A vesícula seminal é composta pelo ducto deferente que apresenta estrutura em espiral que se projeta em formação de curvas por todo o órgão; o ducto possui um epitélio simples colunar com células ciliadas apoiadas sobre a lâmina basal. O epitélio germinativo do testículo é divido em zonas germinativas; a espermatogênese é cística, onde se dá o desenvolvimento das células germinativas em desenvolvimento (espermatogônias, espermatócitos, espermátides e espermatozoides). Cada cisto é formado e mantidos pelas células de Sertoli, que sofrem modificações morfológicas e de localização no decorrer da espermatogênese. Quando na periferia, os cistos formam uma camada em degeneração após a liberação dos espermatozoides para o ducto, que é único e em formato de serpentina. Os órgãos reprodutivos apresentam intrínseca relação entre a sua morfologia e a função de formação, transporte, manutenção e armazenamento dos espermatozoides e líquido espermático, que garantem o sucesso reprodutivo da espécie. A histologia da espermatogênese de Potamotrygon amandae não havia sido descrita anteriormente.
With the filling of the reservoir of the Itaipu Hydroelectric Power Plant, Paraná River, Brazil, from the 1970s onwards, the natural obstacle that isolated part of the Upper Paraná River's ichthyofauna from the fauna of the downstream systems ceased to exist, allowing colonization by species invasive ray Potamotrygon amandae. Chondrichthyes (sharks, rays and chimeras) have a complex reproductive tract, more similar to amphibians and amniotes than teleost fish, formed by testes, epididymis, Leydig's gland and seminal vesicle. Thus, it is of great importance to analyze the functioning of these organs and their respective roles in reproduction. The work aimed to describe the macro and microscopic morphology of the male reproductive tract of Potamotrygon amandae, as well as the description of the spermatogenesis of the species. Male individuals of Potamotrygon amandae (n = 10) were collected in the Jupiá reservoir, Paraná River, Ilha Solteira-SP, anesthetized with MS 222 solution; the reproductive organs were removed, fragmented and fixed in a 4% paraformaldehyde and 2% glutaraldehyde solution in Sorensen phosphate buffer, 0.1M at pH 7.2, and processed for analysis under light microscopy. In P. amandae, the testes are separated from the rest of the tract organs by a thin layer of mesentery, exhibiting well-defined testicular lobes and germinal zones. The other organs are invited to the kidneys, in the dorsal part of the coelomic cavity. The epididymis, an elongated and reddish organ, has a large cranial part, connecting to the Leydig gland at the caudal end. The glands have a narrow cranial portion, large body, reddish color; its caudal portion connects to the seminal vesicle, a long and curvilinear organ, with a hyaline color that extends to the opening of the cloaca. The epididymis is constituted by an anastomosed network of branches originating from the vas deferens formed by ducts and tubules, both of which have the function of transporting sperm and present pseudostratified and columnar stratified epithelium, respectively. The gland is made up of the vas deferens and the glandular tissue that surrounds the duct. The glandular tissue is composed of glandular units of the branched tubular type, with simple columnar epithelium, cells with basal nuclei and apical cytoplasm, mostly secretory, and it is possible to observe secretion in the lumen. A seminal vesicle composed of the vas deferens that has a spiral structure that projects in curves throughout the organ; the duct has a simple columnar epithelium with hair cells resting on the basal lamina. The germinal epithelium of the testis is divided into germinal zones; spermatogenesis is cystic, where the development of developing germ cells (spermatogonia, spermatocytes, spermatids and spermatozoa) takes place. Each cyst is formed and assembled by Sertoli cells, which discover morphology and location during spermatogenesis. When in the periphery, the cysts form a degenerating layer after the release of sperm into the duct, which is unique and serpentine-shaped. The reproductive organs have an intrinsic relationship between their morphology and the function of formation, transport, maintenance and storage of sperm and spermatic fluid, which ensure the reproductive success of the species. The histology of spermatogenesis of Potamotrygon amandae has not been previously described.
With the filling of the reservoir of the Itaipu Hydroelectric Power Plant, Paraná River, Brazil, from the 1970s onwards, the natural obstacle that isolated part of the Upper Paraná River's ichthyofauna from the fauna of the downstream systems ceased to exist, allowing colonization by species invasive ray Potamotrygon amandae. Chondrichthyes (sharks, rays and chimeras) have a complex reproductive tract, more similar to amphibians and amniotes than teleost fish, formed by testes, epididymis, Leydig's gland and seminal vesicle. Thus, it is of great importance to analyze the functioning of these organs and their respective roles in reproduction. The work aimed to describe the macro and microscopic morphology of the male reproductive tract of Potamotrygon amandae, as well as the description of the spermatogenesis of the species. Male individuals of Potamotrygon amandae (n = 10) were collected in the Jupiá reservoir, Paraná River, Ilha Solteira-SP, anesthetized with MS 222 solution; the reproductive organs were removed, fragmented and fixed in a 4% paraformaldehyde and 2% glutaraldehyde solution in Sorensen phosphate buffer, 0.1M at pH 7.2, and processed for analysis under light microscopy. In P. amandae, the testes are separated from the rest of the tract organs by a thin layer of mesentery, exhibiting well-defined testicular lobes and germinal zones. The other organs are invited to the kidneys, in the dorsal part of the coelomic cavity. The epididymis, an elongated and reddish organ, has a large cranial part, connecting to the Leydig gland at the caudal end. The glands have a narrow cranial portion, large body, reddish color; its caudal portion connects to the seminal vesicle, a long and curvilinear organ, with a hyaline color that extends to the opening of the cloaca. The epididymis is constituted by an anastomosed network of branches originating from the vas deferens formed by ducts and tubules, both of which have the function of transporting sperm and present pseudostratified and columnar stratified epithelium, respectively. The gland is made up of the vas deferens and the glandular tissue that surrounds the duct. The glandular tissue is composed of glandular units of the branched tubular type, with simple columnar epithelium, cells with basal nuclei and apical cytoplasm, mostly secretory, and it is possible to observe secretion in the lumen. A seminal vesicle composed of the vas deferens that has a spiral structure that projects in curves throughout the organ; the duct has a simple columnar epithelium with hair cells resting on the basal lamina. The germinal epithelium of the testis is divided into germinal zones; spermatogenesis is cystic, where the development of developing germ cells (spermatogonia, spermatocytes, spermatids and spermatozoa) takes place. Each cyst is formed and assembled by Sertoli cells, which discover morphology and location during spermatogenesis. When in the periphery, the cysts form a degenerating layer after the release of sperm into the duct, which is unique and serpentine-shaped. The reproductive organs have an intrinsic relationship between their morphology and the function of formation, transport, maintenance and storage of sperm and spermatic fluid, which ensure the reproductive success of the species. The histology of spermatogenesis of Potamotrygon amandae has not been previously described.
Descrição
Palavras-chave
Chondrichthyes, Testículo, Epidídimo, Glândula de Leydig, Vesícula seminal, Epididymis, Seminal vesicle, Leydig's gland