Adelina Ferreira

Morfologia oral interna de larvas dos gêneros Eupemphix, Physalaemus e Leptodactylus (Amphibia: Anura)

The internal buccal morphology of the tadpoles of Eupemphix nattereri, Physalaemus albonotatus, P. centralis, P. cuvieri, Leptodactylus furnarius, L. fuscus, L. petersii and L. podicipinus are described and compared using scanning electron microscopy. The tadpole of E. nattereri has major differences when compared to other tadpoles of the Physalaemus genus. The tadpoles of P. albonotatus, P. centralis and P. cuvieri present similarities in internal buccal morphology, such as the number of the infralabial and lateral ridge papillae, but P. centralis differ in the number of the post-narial and buccal roof arena papillae. Among the tadpoles of the Leptodactylus species is possible to observe patterns, in distribution and quantity of the internal buccal structures (infralabial and lingual papillae, buccal floor and roof arena papillae, median ridge, lateral ridge papillae and postnarial papillae) in the species groups. The characteristics of the internal buccal morphology may be useful when used together with other data helping in comprehension of the systematic of the order Anura.

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 Melanorivulusaff. punctatus were collected in a permanent dam in Chapada dos Guimaraes, 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.

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.

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.

Reproductive Strategies of Brazilian Lizards of the Genus Tropidurus Rodrigues, 1987 (Squamata, Tropiduridae) in the Temporal and Spatial

Estrategia reproductiva es el conjunto de adaptaciones que promueven la manera mas eficiente para una poblacion a sobrevivir en las condiciones especificas de un entorno particular. Comprender esta adaptacion es importante y puede identificarse en algunas poblaciones como indicador de cambios ambientales. La espermatogenesis puede ser un proceso biologico medible de estas adaptaciones en escalas espaciales y temporales. Se analizo la morfologia de los testiculos y oviductos de las especies de lagartijas que componen el genero Tropidurus, teniendo en cuenta la amplia distribucion geografica y las relaciones simpatricas. Para el analisis hemos eliminado los testiculos de los machos y la parte media de los oviductos de hembras de las especiesTropidurus Etheridge, T. oreadicus, T. itambere, T. spinulosus y T. Guarani recolectadas en diferentes lugares en el estado de Mato Grosso, Brasil. El periodo reproductivo es sincronico para machos y hembras, y se produce durante septiembre, octubre y noviembre. Se caracterizaron como machos reproductores por testiculos con tubulos seminiferos con celulas germinales en distintas etapas de la espermatogenesis, un epitelio muy alto, un lumen reducido, numerosos espermatozoides libres en el lumen y tejido intersticial redicudo. En hembras el pico reproductivo se produce cuando los canales de conduccion de gametos poseen un epitelio alto, secretor y con nucleos basales. Estos meses son caracterizados en las zonas muestreadas por fuertes lluvias y altas temperaturas. La disminucion del periodo reproductivo se observo en ambos sexos, entre abril y agosto. La baja reproduccion en machos se caracteriza por un lumen ancho, ausencia de espermatozoides, presencia de celulas germinales solo en las primeras etapas de la espermatogenesis (espermatogonias y pocos espermatocitos) y tejido intersticial amplio. En las mujeres, el periodo de baja reproduccion esta marcado por la ausencia de glandulas unicelulares en el epitelio del oviducto, con mayor afinidad a la tincion. Este periodo corresponde al de baja precipitaciones y temperaturas mas bajas. Proponemos un analisis de muestras de las colecciones zoologicas ya que esta es una propuesta para facilitar el trabajo de muchos investigadores a traves del acceso a las especies, especialmente especies raras.

Ultrastructural immunocytochemical evidence for actin in the acrosomal complex during spermiogenesis of the lizard Tropidurus itambere (Rodrigues, 1987) (Reptilia: Tropiduridae)

Abstract During spermiogenesis of the lizard Tropidurus itambere early developmental stages of the acrosomal complex have been analysed and new suggestions made as to their origin. Actin has been detected in the acrosomal granule and pro-acrosomal vesicle of spermatid, using an antibody for α-smooth muscle actin (monoclonal α-SMA). Intense marking also identified actin in two regions of the acrosomal complex; the subacrosomal cone and the perforatorium. The acrosomal and subacrosomal granules appear to participate to the formation of the perforatorium, while the pro-acrosomal vesicle is responsible for the formation of the subacrosomal cone. The results therefore endorse the view that, in lizards, the perforatorium and subacrosomal cone are homologous, in composition and probably also in function.

Morfologia bucal interna dos girinos de Leptodactylus labyrinthicus Spix, 1824 (Amphibia: Anura: Leptodactylidae)

The microanatomy of the oral disc and the buccal cavity of the tadpole of Leptodactylus labyrinthicus is described and compared with other species included in the L. pentadactylus species group. Thirty-five tadpoles between stages 25 and 46 had been dissected and analyzed in scanning electron microscopy. The oral and internal buccal morphology was analyzed in tadpoles between stages 36 and 39. The buccal morphology of the tadpole of L. labyrinthicus is similar to other tadpoles with adaptation to macrophagy, such as the strong queratinization of the jaw, reduction of the internal buccal structures and presence of one glote uncovered, propitious to carnivorous diets. The tadpole of L. pentadactylus species group share this trend to the reduction of the structures of selection and capture of particle, including reduction in the number of the buccal roof and floor arena papillae, reduction or absence of anterior papillae on the buccal pocket, only two postnarial papillae, small lateral ridge papillae and glandular zones restricted in narrow bands on the edge of velum. In the tadpoles of genera Leptodactylus the larval morphology reflects the current groups considered for this genera.