Isolation, in vitro study, and stem cell markers for type A spermatogonia in a Characiformes species.

The objective of this study was to establish a protocol for the characterization, isolation, and culture of type A spermatogonia using specific molecular markers for these cells in fish. To this end, adult Prochilodus lineatus testes were collected and digested enzymatically and the resulting testicular suspension was separated using a discontinuous Percoll gradient, followed by differential plating. The cell cultures obtained were monitored for 15 days and analyzed using the immunofluorescence method with anti-Vasa, anti-GFRα1, and anti-OCT4 antibodies. Spermatogonial enrichment was also performed using flow cytometry. Although discontinuous Percoll gradient centrifugation followed by differential plating enabled the removal of differentiated germ cells and somatic cells, enriching the pool of type A spermatogonia, the enrichment of type A spermatogonia through flow cytometry of samples without Percoll proved to be more efficient. Prominent cell agglomerates that were characterized according to different stem cell markers as type A spermatogonia were observed during the 15 days of the cell culture. The use of immunoperoxidase and western blot analysis methods confirmed the specificity of the markers for type A spermatogonia of P. lineatus. When combined with specific cell culture conditions, the positive characterization of these molecular markers clarified certain aspects of spermatogonial regulation, such as survival and proliferation. Finally, understanding the regulation of the in vitro germ cell maintenance process may contribute to the enhancement of in vivo and in vitro reproduction techniques of endangered or aquaculture fish species.

Molecular characterization of different preproGnRHs in Astyanax altiparanae (Characiformes): Effects of GnRH on female reproduction.

Gonadotropin-releasing hormone (GnRH) is a key molecule in the initiation of the hypothalamic-pituitary-gonadal axis. Thus, knowledge about GnRH may contribute to the effectiveness of species reproduction. Using a Neotropical tetra Astyanax altiparanae as a fish model species, the GnRH forms were characterized at the molecular level and the role of injected GnRHs in vivo was evaluated. The full-length complementary DNA (cDNA) sequences of preproGnRH2 (612 bp) and preproGnRH3 (407 bp) of A. altiparanae were obtained, and the GnRH1 form was not detected. The cDNA sequences of preproGnRH2 and preproGnRH3 were found to be conserved, but a change in the amino acid at position 8 of the GnRH3 decapeptide of A. altiparanae was observed. All the injected GnRHs stimulated lhß messenger RNA (mRNA) expression but not fshß mRNA expression, and only GnRH2 was able to increase maturation-inducing steroid (MIS) levels and possibly stimulate oocyte release. Furthermore, only GnRH2 was able to start the entire reproductive hormonal cascade and induce spawning.

Follicular Development and Reproductive Characteristics in Four Species of Brazilian Tropidurus Lizards.

The follicular development and reproductive characteristics of four species of oviparous lizards in the Tropidurus torquatus group were anatomically and histologically evaluated. We measured specimens, recorded the number of follicles and eggs, and removed the right ovary of each individual, which we processed according to histological routine and photo-documented. For all species, ovaries were divided into a cortical germinal bed, where oogonia and stage I oocytes are located, and a medullar stroma, where the remaining follicular developmental stages occur. Microscopic analysis did not show differences in ovarian follicle development for the four species of the T. torquatus group. The only measurement that presented significant variation throughout follicular development was the thickness of the granulosa layer in stage VII follicles. Regarding snout-tovent length at sexual maturity, few variations were observed among the species, with the smallest length recorded for T. oreadicus. Clutch size was higher for T. itambere and T. torquatus species, with a maximum of five and six eggs in the oviducts, respectively. Tropidurus oreadicus and T. hispidus had a maximum of five and six follicles, respectively, but neither species presented eggs in the oviducts. In addition, the reproductive activity varied among the four lizard species of the T. torquatus group. Finally, besides the morphological characteristics observed among these species, this is the first study to report data on the germinal bed, number of ovarian follicles, corpus luteum, and follicular atresia in relation to reproductive activity.

Ovarian development and the reproductive profile of Astyanax altiparanae (Teleostei, Characidae) over one year: Applications in fish farming.

Astyanax altiparanae is a Brazilian species of substantial commercial, environmental and scientific importance; however, existing studies on its reproduction do not seem to provide enough details. In light of the increasing use of this species in fish farming and the need for basic studies for the development of new production technologies, we describe the structural and ultrastructural characteristics of the ovaries of A. altiparanae, and characterize the species' reproductive cycle. Females were collected monthly from March 2013 to February 2014, and reproductive management began in October 2013. The ovaries were removed, fixed in Karnovsky's fixative, and prepared for light microscopy, transmission electron microscopy and immunohistochemistry anti-PCNA. These techniques enabled us to characterize the ovaries, the germ cells, and the somatic cells in detail, as well as their changes over time. The reproductive cycle was characterized based on the monthly variation in the gonadosomatic ratio, the proportion of germ cells, and the rate of oogonium proliferation. The macroscopic analysis of the ovaries suggests that the vascularization pattern and color of the ovaries vary according to development. There are new types of analyses that can be applied even in the fish farming industry, such as a comparison between ovaries staining and weight or the frequency distribution of these colors throughout the year. This study also provides details on microscopic characteristics that have never before been reported for species of Astyanax, such as the presence of annulate lamellae in oogonia, the development of the zona pellucida from oocytes in the one-nucleolus step, and the development of the micropylar apparatus in oocytes in the cortical alveolar step. When the reproductive cycle was analyzed, this species was found to have a long period of spawning, with a reproductive peak from October to February and multiple spawning events, confirming the period already described in the literature. Variations in reproductive periods and the ability to reproduce in lentic environments suggest that A. altiparanae has the ability to respond quickly to environmental changes and exhibits high reproductive flexibility. All of these characteristics confirm the great potential of this species in the fish farming industry.

Characterization of undifferentiated spermatogonia and the spermatogonial niche in the lambari fish Astyanax altiparanae.

Undifferentiated type A spermatogonia are the foundation of fish spermatogenesis. This cell population includes the spermatogonial stem cell population, which is able to either self-renew or differentiate into cells that will generate the male gamete - the spermatozoa. Spermatogonia stem cells are located in a specific region of the testes known as the spermatogonial niche, which regulates spermatogonial stem cell function. This study characterizes undifferentiated type A spermatogonia and their S-phase label-retaining cell properties in Astyanax altiparanae testes. This is a fish species of substantial commercial, environmental, and academic importance. Two types of undifferentiated spermatogonia have been described in A. altiparanae testis: Aund* and Aund. Among the main differences observed, Aund* spermatogonia have an irregular nuclear envelope, decondensed chromatin, one or two nucleoli, and nuages in the cytoplasm; meanwhile, type Aund have a round nucleus. Aund* is preferentially distributed in areas neighboring the interstitial compartment, whereas Aund is located in the intertubular area. Finally, this study found that undifferentiated type A spermatogonia were able to retain BrdU over a long chase period, suggesting that these cells have a long cell cycle and potential stem cell candidates among them. Based on these findings, undifferentiated type A spermatogonia may be characterized as putative stem cells in A. altiparanae testis. This work will contribute to further studies on the stem cell biology of this promising Neotropical experimental model.

Involution processes of follicular atresia and post-ovulatory complex in a characid fish ovary: a study of apoptosis and autophagy pathways.

Recent studies seem to indicate that apoptosis and autophagy can act cooperatively in fish ovaries in order to achieve more effective ovarian regression after spawning. Considering the importance of tissue remodeling in ovarian functioning, we sought to morphologically characterize the involution processes of follicular atresia and post-ovulatory complexes using Astyanax altiparanae as an experimental model, and to determine the location of proteins involved in apoptosis and autophagy throughout this process. Fifteen females were collected after reproductive management. Fragments of the left ovaries were removed, fixed, and prepared for light microscopy and immunofluorescence analyses. The main characteristics of the involution processes were found to be consistent with previous descriptions. However, there were certain morphological peculiarities that do not appear to have been described for any other species thus far. These peculiarities may be related to the focus of this study on a single species, which allows for a more detailed investigation into morphological changes than studies on multiple species. Autophagy was also found to precede apoptosis in both involution processes in A. altiparanae. This may be related to the energy recycling process required before the removal of degenerated follicular cells by apoptosis. Thus, these results support the idea that there is crosstalk between autophagy and apoptosis pathways in ovarian involution processes, as well as the idea that the cell death pathways of these processes are conserved between teleost species with external fertilization.

Spermatogonia, Germline Cells, and Testicular Organization in the Characiform Prochilodus lineatus Studied Using Histological, Stereological, and Morphometric Approaches.

Prochilodus lineatus is an important representative of the order Characiformes and a species that offers great advantages to fish farming. Therefore, detailed knowledge of its reproductive biology can be applied to various fields of production and biotechnology. In this study, we have identified testicular germ cells during spermatogenesis and have evaluated the volumetric proportion of the testes occupied by structures of the tubular and intertubular compartments. In addition, the individual volume of type A spermatogonia was measured and used to estimate the mean number of these cells per testis. Gonads of adult P. lineatus males were extracted and fixed. Light and transmission electron microscopy were applied to fragments of three testicular regions. Histological, stereological, and morphometric analyses were performed. The stereological data suggest that components of the tubular and intertubular compartments of the P. lineatus testes present a uniform distribution in all three regions and therefore reflect regions with similar distributions of cell types. In addition, P. lineatus testes showed ∼0.6% of type A spermatogonia, as well as a predominance of cysts of primary spermatocytes and spermatids during the reproductive phase evaluated. The results from this study provide a better understanding of the morphology and structure of the testis and of the characterization of the type A spermatogonia in P. lineatus. The nuclear diameter of germ cells also decreases significantly during spermatogenesis. The data presented herein are the first of its kind for the order Characiformes and may be useful for future biotechnology studies on fish reproduction. Anat Rec, 300:589-599, 2017. © 2016 Wiley Periodicals, Inc.

Gonadotropin subunits of the characiform Astyanax altiparanae: Molecular characterization, spatiotemporal expression and their possible role on female reproductive dysfunction in captivity.

To better understand the endocrine control of reproduction in Characiformes and the reproductive dysfunctions that commonly occur in migratory fish of this order when kept in captivity, we chose Astyanax altiparanae, which has asynchronous ovarian development and multiple spawning events, as model species. From A. altiparanae pituitary total RNA, we cloned the full-length cDNAs coding for the follicle-stimulating hormone ß subunit (fshb), the luteinizing hormone ß subunit (lhb), and the common gonadotropin α subunit (gpha). All three sequences showed the highest degree of amino acid identity with other homologous sequences from Siluriformes and Cypriniformes. Real-time, quantitative PCR analysis showed that gpha, fshb and lhb mRNAs were restricted to the pituitary gland. In situ hybridization and immunofluorescence, using specific-developed and characterized polyclonal antibodies, revealed that both gonadotropin ß subunits mRNAs/proteins are expressed by distinct populations of gonadotropic cells in the proximal pars distalis. No marked variations for lhb transcripts levels were detected during the reproductive cycle, and 17α,20ß-dihydroxy-4-pregnen-3-one plasma levels were also constant, suggesting that the reproductive dysfunction seen in A. altiparanae females in captivity are probably due to a lack of increase of Lh synthesis during spawning season. In contrast, fshb transcripts changed significantly during the reproductive cycle, although estradiol-17ß (E2) levels remained constant during the experiment, possibly due to a differential regulation of E2 synthesis. Taken together, these data demonstrate the putative involvement of gonadotropin signaling on the impairment of the reproductive function in a migratory species when kept in captivity. Future experimental studies must be carried to clarify this hypothesis. All these data open the possibility for further basic and applied studies related to reproduction in this fish model.

Induced reproduction in a migratory teleost species by water level drawdown

Captive reproduction is one of the problems faced in aquaculture requiring the manipulation of environmental factors and/or hormonal treatment. Thus, we seek to verify experimentally which gonadal changes were present in mature individuals of Astyanax altiparanae arising from decreased water level. Collections were made every four hours, initiated four hours before and finished 28 hours after stimulation, at the Fish Farming Station of Companhia Energética de São Paulo, São Paulo, Brazil. The gonads were analyzed by light microscopy. The females had ovaries in the spawning capable phase until 12h; in 16h, in a more advanced stage of spawning capable phase; and, from 20h, in the regressing phase. Males had testes in the spawning capable phase until 8h; in 12h, in a more advanced stage of spawning capable phase; and, from 16h, the return to the spawning capable phase. The morphological description was corroborated by the proportion of cell classes. Females presented variation on the gonadosomatic index, but it was not found an emptying of the gonad for neither sex. The process of inducing reproduction with water level drawdown was considered satisfactory, since both sexes presented a reduction in the number of mature gametes at the end of the sample period.

Reprodução em cativeiro é um dos problemas enfrentados na aquicultura exigindo a manipulação de fatores ambientais e/ou tratamento hormonal. Assim, verificou-se experimentalmente as alterações gonadais presentes em indivíduos adultos de Astyanax altiparanae decorrentes da diminuição do nível da água. As coletas foram realizadas a cada quatro horas, iniciadas quatro horas antes e encerradas 28 horas após a estimulação, na Estação de Piscicultura da Companhia Energética de São Paulo, São Paulo, Brasil. As gônadas foram analisadas por microscopia de luz. As fêmeas apresentaram ovários na fase de apto à reprodução até 12h; em 16h, um estágio mais avançado desta fase; e, a partir das 20h, na fase de regressão. Os machos tiveram os testículos em fase de apto à reprodução até 8h; em 12h, um estágio mais avançado desta fase; e, a partir das 16h, o retorno à fase de apto à reprodução. A descrição morfológica foi corroborada pela proporção das classes celulares. As fêmeas apresentaram variação no índice gonadossomático, mas não foi estabelecido o esvaziamento das gônadas para nenhum dos sexos. O processo utilizado para a indução à reprodução foi considerado satisfatório, uma vez que ambos os sexos apresentaram redução no número de gametas maduros no final do período de amostragem.

Ultrastructural features of spermatogenesis in Melanorivulus punctatus (Cyprinodontiformes: Rivulidae).

Fish belonging to the family Rivulidae possess one of the most complex reproductive systems. Rivulus, a genus of freshwater fish in the Rivulidae family, was recently reclassified into five genera, including Melanorivulus. Its type species, M. punctatus, is widely distributed and probably represents a species complex. The ultrastructure of sperm has been broadly used in systematics, and we hereby describe the ultrastructural features of spermatogenesis in M. punctatus. Ten M. punctatus males were collected from the reservoir of Parque Estadual da Quineira, municipality of Chapada dos Guimarães, Mato Grosso, Brazil, and prepared for analysis by light microscopy and transmission electron microscopy. M. punctatus undergoes cystic spermatogenesis. Its cysts consist of groups of germ cells that are in synchronous development and are surrounded by cytoplasmic projections of Sertoli cells. With the breakdown of the cysts, the spermatozoa are released and their maturation is completed in the duct, where part of the cytoplasmic material is discarded through the vesicles. The mature spermatozoon is characterized by a spherical head with homogeneously condensed chromatin, a symmetric midpiece consisting of a pair of perpendicular centrioles, a ring of mitochondria, several vesicles, and one flagellum medial to the nucleus. Early stages of spermatogenesis show no peculiarities; however, in spermiogenesis, we observed that the spermatids remain interconnected by cytoplasmic bridges and have pockets of residual cytoplasm. The sperm is of the aquasperm type and is similar to that observed in the members of the family Rivulidae. The spermatozoa have a single flagellum that consists of a classic axoneme (9+2), as found in most groups of fish, despite the lateral extensions.

Morphologic study of the liver of lambari (Astyanax altiparanae) with emphasis on the distribution of cytokeratin.

Studies on the morphology of the liver of teleosts reflect some controversy in the interpretation of the data, but also provide confirmation of variations in the structure of the organ in several species. Thus, we intend to understand the specific structural organization of the liver of Astyanax altiparanae. Specimens were collected in the city of Andirá, Paraná, Brazil. The livers were processed according to histological routine for inclusion in Paraplast, and the sections were stained with HE and Mallory's trichrome or followed the protocol for fluorescence immunohistochemistry, anti-cytokeratin. The liver of A. altiparanae was covered by a capsule of connective tissue, without delimiting lobes. The hepatocytes had an arrangement in cords around sinusoids. Melanomacrophage centers were observed. The vascular components and intrahepatic pancreatic acini were distributed between hepatocytes. Presence of cytokeratin was detected in tissues that lined the liver and endothelial cells of sinusoids. The comparison of the liver of A. altiparanae to other characids corroborates with the fact that there is variation in the morphology of the liver even between closely related species. Moreover, it appears that in this species, endothelial cells of sinusoids can synthesize the cytokeratin filaments required for the regulation of blood flow in capillaries in adults.

Gametogenesis and reproductive cycle of Melanorivulus aff. punctatus (Boulenger, 1895) (Cyprinodontiformes, Rivulidae) in Chapada dos Guimarães, Mato Grosso, Brazil

The comprehension of the reproductive cycle allows to understand which are the morphological changes that develop in the gonad during this interval. Thus, many studies have been undertaken in order to describe and classify the stages of gonadal development and reproductive status of Neotropical fishes. For this purpose, specimens of Melanorivulus aff. punctatus were collected in a permanent dam in Chapada dos Guimarães, Mato Grosso, Brazil. The gonads were prepared for analysis by light microscopy. The oogenesis and spermatogenesis have been described, characterizing the stages of gonadal development, together with assessments of the gonadosomatic ratio, germ cell count and verification of variation of mature oocytes in females. Throughout the year the male gonads presented themselves as capable of reproducing, characterized by the presence of undifferentiated and differentiated spermatogonia, spermatocytes organized into cysts, spermatids in cysts whose wall was thicker and the spermatozoa was free in the lumen and the duct. This can indicate a continuous reproductive cycle with split spermiation. The females had gonads in the development stage from May to September with undifferentiated and differentiated oogonias and early oocytes always facing the lumen, abundant pre-vitellogenic and vitellogenic oocytes and some atresias. In the phase capable of spawning, observed from October to March, the mature oocytes are abundant, there are many post-ovulatory complexes and some atresia in advanced stage. The regression, observed in some individuals from February to April, is characterized by ovaries with many atresias and post-ovulatory complexes. The same results were found in the quantitative assessments. Therefore, it may be characterized as discontinuous cycle with split spawning. Thus, the reproductive cycle of this species can be characterized as continuous for males and discontinuous for females, which have a most intense phase of reproduction from October to March. However, both have fractional release of gametes.

A compreensão do ciclo reprodutivo possibilita entender quais são as mudanças morfológicas que se desenvolvem na gônada neste período. Assim, muitos estudos têm sido realizados no intuito de descrever e classificar as fases de desenvolvimento gonadal e dos estados reprodutivos dos peixes da região Neotropical. Com esse objetivo foram coletados espécimes de Melanorivulus aff. punctatus em um represamento permanente em Chapada dos Guimarães, Mato Grosso, Brasil. As gônadas foram preparadas para análise à microscopia de luz. A ovogênese e a espermatogênese foram descritas e caracterizados os estágios de desenvolvimento gonadal, juntamente com as avaliações de razão gonadossomática, contagem de células germinativas e verificação de variação de ovócitos maduros em fêmeas. Durante todo o ano as gônadas masculinas apresentaram-se como aptas a reprodução, caracterizadas pela presença de espermatogônias indiferenciadas e diferenciadas, espermatócitos organizados em cistos, espermátides em cistos com parede mais espessa e espermatozoides livres no lúmen e no ducto. Isso pode indicar um ciclo reprodutivo contínuo com espermiação parcelada. As fêmeas apresentaram gônadas em estágio de desenvolvimento de maio a setembro, com ovogônias indiferenciadas e diferenciadas e ovócitos iniciais sempre voltados para o lúmen, ovócitos pré-vitelogênicos e vitelogênicos abundantes e algumas atresias. Na fase de apto a desova, observada de outubro a março, os ovócitos maduros são abundantes, há muitos complexos pós ovulatórios e algumas atresias em estágio avançado. A fase de regressão, constatada em alguns indivíduos de fevereiro a abril, é caracterizada por ovários com muitas atresias e complexos pós-ovulatórios. Os mesmos resultados foram encontrados nas avaliações quantitativas realizadas. Logo, pode-se caracterizar o ciclo como descontínuo com desova parcelada. Assim, o ciclo reprodutivo desta espécie pode ser caracterizado como contínuo para machos e descontínuo para fêmeas, que apresentam uma fase mais intensa de reprodução de outubro a março. Porém, ambos possuem liberação de gametas parcelada.

Cytoarchitectonical dynamic of Sertoli cells in Melanorivulus punctatus (Cyprinodontiformes: Rivulidae).

The Sertoli cell contributes to spermatogenesis acting in the differentiation of germ cells and being the only somatic cells present in the germinal compartment. So that spermatogenesis is primarily dependent of Sertoli-Sertoli and Sertoli-germ cell interactions once Sertoli cells provide critical factors necessary for a successful differentiation of germ cells to sperm. In teleost fish the cytoplasmic extensions of Sertoli cells support the cysts that remain closed until spermiogenesis. The number of Sertoli cells determines the testicular size, the number of testicular germ cells and the production capacity of spermatozoa. Our objective was to describe the morphology and the cytoarchitectonical dynamic of Sertoli cells in Melanorivulus punctatus, which were collected in the municipality of Chapada dos Guimarães, Mato Grosso, Brazil. The gonads were extracted and prepared according to histological routine for light microscopy and transmission electron microscopy. Sertoli cells have cytoplasmic extensions which provide the conformation of cysts in the interior of the lobes. These cells possess a polymorphic nucleus with a well-defined nuclear envelope and a prominent and eccentric nucleoli. Each cyst is sustained for more than one Sertoli cell and the cysts seem to share the Sertoli cells with each other regardless the stage of development of germ cells within these cysts. This disposal promotes a reticulated arrangement of Sertoli cells. The Sertoli cells lining the ducts assume rectangular shape with rounded nucleus. Thus, the morphological characteristics of Sertoli cells observed did not differ from what has been described for other teleosts. Despite the similarity in the morphology of these cells, we observed that its disposal in the extension of the gonad seems to differ from what is described for fish. The arrangement by which the cytoplasmic extensions of Sertoli cells connect the ends of lobes prevents the proliferation of spermatogonia on the lobe side walls and are only observed in the end of the lobes, which ensures the testicular characteristic-lobular restricted in Atherinomorpha.

Histological evidence of reproductive activity in lizards from the APM Manso, Chapada dos Guimarães, Mato Grosso State, Brazil - doi: 10.4025/actascibiolsci.v34i3.9228

The construction of dams causes major impacts on fauna by changing or eliminating irreversibly their habitats. The resulting changes lead to deep potential modifications on reproductive biology and population structure of lizards, snakes and amphisbaenas. The reservoir in the Multiple Use Area of Manso (APM-Manso) is located near to Chapada dos Guimarães National Park, in Mato Grosso State. We analyzed comparatively the male gonads of Anolis meridionalis, Colobosaura modesta, Cercosaura ocellata, Cnemidophorus ocellifer, Hoplocercus spinosus, Bachia bresslaui, Mabuya frenata, Micrablepharus atticolus and Tropidurus oreadicus, from APM-Manso, aiming to verify possible changes in the reproductive success according to environmental changes. Before the impoundment  A. meridionalis, Colobosaura modesta, Cercosaura ocellata, M. atticolus and T. oreadicus showed up reproductive. However, during the impoundment period they presented changes in seminiferous tubules, evidenced by the absence of spermatids and spermatozoids. B. bresslaui and M. frenata had no differences in the seminiferous tubules before and after the impoundment, being reproductive in both moments. The damming and the formation of the lake of Manso reservoir may have interfered on the reproduction of some lizards species, especially if the reproductive cycle is regulated by the rainfall of the habitat.

Histological evidence of reproductive activity in lizards from the APM Manso, Chapada dos Guimarães, Mato Grosso State, Brazil / Evidências histológicas da atividade reprodutiva em lagartos da região da APM Manso, Chapada dos Guimarães, Estado do Mato Grosso, Brasil

The construction of dams causes major impacts on fauna by changing or eliminating irreversibly their habitats. The resulting changes lead to deep potential modifications on reproductive biology and population structure of lizards, snakes and amphisbaenas. The reservoir in the Multiple Use Area of Manso (APM-Manso) is located near to Chapada dos Guimarães National Park, in Mato Grosso State. We analyzed comparatively the male gonads of Anolis meridionalis, Colobosaura modesta, Cercosaura ocellata, Cnemidophorus ocellifer, Hoplocercus spinosus, Bachia bresslaui, Mabuya frenata, Micrablepharus atticolus and Tropidurus oreadicus, from APM-Manso, aiming to verify possible changes in the reproductive success according to environmental changes. Before the impoundment A. meridionalis, Colobosaura modesta, Cercosaura ocellata, M. atticolus and T. oreadicus showed up reproductive. However, during the impoundment period they presented changes in seminiferous tubules, evidenced by the absence of spermatids and spermatozoids. B. bresslaui and M. frenata had no differences in the seminiferous tubules before and after the impoundment, being reproductive in both moments. The damming and the formation of the lake of Manso reservoir may have interfered on the reproduction of some lizards species, especially if the reproductive cycle is regulated by the rainfall of the habitat.

A construção de barragens tem ocasionado grandes impactos sobre a fauna ao alterar ou eliminar seus habitats de forma irreversível. Alterações decorrentes exercem profundas modificações potenciais na biologia reprodutiva e na estrutura populacional de lagartos, serpentes e anfisbenas. O reservatório da Área de Aproveitamento Múltiplo de Manso (APM-Manso) localiza-se próximo ao Parque Nacional da Chapada dos Guimarães, em Mato Grosso. Foram analisadas comparativamente as gônadas masculinas de Anolis meridionalis, Colobosaura modesta, Cercosaura ocellata, Cnemidophorus ocellifer, Hoplocercus spinosus, Bachia bresslaui, Mabuya frenata, Micrablepharus atticolus e Tropidurus oreadicus, da APM-Manso com o objetivo de verificar se houve alterações no sucesso reprodutivo das mesmas de acordo com as modificações ocorridas no ambiente. Antes do represamento A. meridionalis, Colobosaura modesta, Cercosaura ocellata, M. atticolus e T. oreadicus apresentavam-se reprodutivas. No entanto, durante o período de represamento apresentaram alterações nos túbulos seminíferos evidenciadas pela ausência de espermátides e espermatozóides. B. bresslaui e M. frenata não apresentaram diferenças em seus túbulos seminíferos antes ou depois do represamento, estando reprodutivas em ambos os momentos. O represamento e a formação do lago do Manso pode ter interferido na reprodução de algumas espécies de lagartos, principalmente se o ciclo reprodutivo for regulado a partir da pluviosidade do habitat.