Características estruturais e ultraestruturais da espermatogênese do cascudo-cinza Liposarcus anisitsi (Holmberg, 1893) (Teleostei, Siluriformes)

Liposarcus anisitsi é um teleósteo de água doce da ordem Siluriforme, com fertilização externa, possui um processo de espematogênese cística com estrutura espermatogonial lobular irrestrita dos testículos. Nesta espécie, a espermatogônia primária intracística ou isolada é considerada como a "stem cell" da linhagem espermatogenética. Então, como consequência do processo da espermatogênese cística de Liposarcus anisitsi todas as três células germinativas são observadas no interior de cistos espermatogenéticos específicos, desde as espermatogônias primárias e secundárias até os espermatócitos e espermátides jovens e maduras. A espermatogônia possui forma esférica, com núcleo central e grande quantidade de mitocôndrias redondas e retículo endoplasmático, principalmente do tipo rugoso, em seu citoplasma. Os espermatócitos primários se inter-relacionam através de pontes citoplasmáticas e são claramente identificados pela presença de complexos sinaptonêmicos no interior de seus núcleos. Espermátides jovens no início da fase maturacional, tanto quanto as espermátides maduras tendem a exibir núcleos esféricos, um modelo variável de progressiva condensação cromatínica durante o estágio final da espermiogênese. Nestes estágios finais, as espermátides maduras mostra uma fossa nuclear formada para a fixação do flagelo. O espermatozóide de Liposarcus anisitsi possui cabeça redonda, núcleo redondo, cromatina densa, ausência de acrossoma, curta peça intermediária e longa cauda (peças principal e terminal do flagelo).Liposarcus anisitsi is a freshwater teleost from Siluriform order with external fertilization that shows cystic spermatogenesis process with spermatogonial unrestricted lobular structure of the testes. In this species, isolated or intracystic primary spermatogonia were noted as the ¨stem cells¨ of the spermatogenetic lineage. Thus, as consequence of the cystic spermatogenesis process of Liposarcus anisitsi all the three germinative cells are observed inside specific spermatogenetic cysts, since the primary and secondary spermatogonias until the spermatocytes and early and late spermatids. Spermatogonia show spherical shape with central nuclei and great amount of round mitochondria and ER profiles mainly of rough type in their cytoplasm. Primary spermatocytes have inter-relations through cytoplasmic bridges and are clearly identified by presence of synaptonemic complexes inside the nuclei. Early spermatids beginning maturational phases, as well as the late spermatids, tend to exhibit spherical nuclei, variable chromatin pattern with progressive condensation during the end steps of the spermiogenesis. In this end steps, the late spermatids show the nuclear fossa formed to the fixation of the flagella. The spermatozoon of Liposarcus anisitsi shows round head, round nuclei, very dense chromatin, lack of acrosoma, short middle piece and long tail (principal and end pieces of the flagellum)

Polinização de Pagamea duckei Standl. (Rubiaceae): Uma espécie funcionalmente dióica

The floral biology, pollination and breeding system of Pagamea duckei Standl. (Rubiaceae) were studied at the Reserva Biológica da Campina, Manaus, Amazonas, Brazil. Floral morphology suggested that P. duckei is a distylous species. However, crossing experiments revealed that it is functionally dioecious. The flowers are actinomorphic, yellowish, produce nectar and a sweet odor, which is more intense in the morning. Anthesis started in the morning between 5.00 and 6.00 AM and extended until dusk, when the corolla tube abscissed. The flowers were visited mostly by bees of the genus Melipona. Pagamea duckei is not agamospermic and thus needs pollen vectors for effective pollination. The results of this study strengthen the idea that, in Pagamea, species with distylous flower morphology are actually functionally dioecious

Morphological characteristics of the ventricular myocardium of Tambaqui (Colossoma macropomun; Characidae, Cuvier, 1818)

O Colossoma macropomun, peixe teleósteo com hábito natatório intenso, apresentou ventrículo cardíaco com forma piramidal e miocárdio com estrutura mista, sendo formada por uma camada compacta externa e outra esponjosa interna. Esta estrutura bilaminar diferenciada, atualmente, tem sido correlacionada com o hábito natatório e com a morfologia ventricular.The neotropical teleost fish Colossoma macropomun an active swimming species showed cardiac ventricle with pyramidal shape and myocardium with mixed structure. The myocardium presented an outer compact layer and an inner spongy layer whose particular bilaminar structure hitherto has been correlated to swimmer habit as well as to ventricular shape

Morphological characteristics of the ventricular myocardium of Tambaqui (Colossoma macropomun; Characidae, Cuvier, 1818)

O Colossoma macropomun, peixe teleósteo com hábito natatório intenso, apresentou ventrículo cardíaco com forma piramidal e miocárdio com estrutura mista, sendo formada por uma camada compacta externa e outra esponjosa interna. Esta estrutura bilaminar diferenciada, atualmente, tem sido correlacionada com o hábito natatório e com a morfologia ventricular.The neotropical teleost fish Colossoma macropomun an active swimming species showed cardiac ventricle with pyramidal shape and myocardium with mixed structure. The myocardium presented an outer compact layer and an inner spongy layer whose particular bilaminar structure hitherto has been correlated to swimmer habit as well as to ventricular shape

Morphological examination of the epididymal duct in the dog

The epithelium lining of the epididymal duct is pseudostratified columnar and the cell population is comprised of principal, basal, and apical cells. The stroma periductal, is a well developed framework surrounding the tubule. Epididymal epithelial heights were maximal in the initial segment and minimal in the tail. Luminal diameter was just the reverse of the last pattern, e.g., it increased along the length of the duct.O ducto epididimário, no cão, acha-se revestido por epitélio colunar pseudoestratificado, com população celular constituída por células principais, basais e apicais, presentes em todas as regiões. Este epitélio é circundado pelo estroma peritubular. O epitélio do segmento inicial epididimário possui a maior altura, que diminui progressivamente em direção à cauda epididimária. Ocorre um aumento progressivo do lúmen tubular através das diferentes regiões, sendo maior na região da cauda epididimária, configurando um local de estocagem de espermatozóides

Anatomical pattern of the umbilical artery (round lig. of the urinary bladder) and urogenital artery in the guinea pig (Cavia porcellus, L., 1756)

This work deals with the study of the visceral branches of the internal iliac artery in guinea pig. Twenty animals (10 males and 10 females), adults were sacrificed with ethylic ether, injected with contrasting substance into abdominal aorta and dissected through stereoscopic microscope. In results were described the origin and permeability of the umbilical artery and the origin and branching of the urogenital artery. These observations in the guinea pig were comparatively discussed with others similarly described in several mammalians including: another laboratorial rodents, cat, dog, rabbit and man.Foi realizado estudo anatômico dos ramos viscerais da a. ilíaca interna na cobaia. Foram utilizadas 20 cobaias (10 machos e 10 fêmeas), adultas, sacrificadas com éter etílico (saturação anestésica), injetadas com contraste na aorta abdominal (látex corado) e dissecadas sob lupa. Em resultados são descritas a origem e a perviedade da a. umbilical e a origem e a ramescência da a. urogenital. Estas observações na cobaia foram comparativamente discutidas com outras semelhantemente descritas em diferentes mamíferos incluindo: outros roedores de laboratório, gato, cão, coelho e Homem

Rarity of monodominance in hyperdiverse Amazonian forests.

Tropical forests are known for their high diversity. Yet, forest patches do occur in the tropics where a single tree species is dominant. Such "monodominant" forests are known from all of the main tropical regions. For Amazonia, we sampled the occurrence of monodominance in a massive, basin-wide database of forest-inventory plots from the Amazon Tree Diversity Network (ATDN). Utilizing a simple defining metric of at least half of the trees ≥ 10 cm diameter belonging to one species, we found only a few occurrences of monodominance in Amazonia, and the phenomenon was not significantly linked to previously hypothesized life history traits such wood density, seed mass, ectomycorrhizal associations, or Rhizobium nodulation. In our analysis, coppicing (the formation of sprouts at the base of the tree or on roots) was the only trait significantly linked to monodominance. While at specific locales coppicing or ectomycorrhizal associations may confer a considerable advantage to a tree species and lead to its monodominance, very few species have these traits. Mining of the ATDN dataset suggests that monodominance is quite rare in Amazonia, and may be linked primarily to edaphic factors

Pollination of Pagamea duckei Standl. (Rubiaceae): a functionally dioecious species

The floral biology, pollination and breeding system of Pagamea duckei Standl. (Rubiaceae) were studied at the Reserva Biológica da Campina, Manaus, Amazonas, Brazil. Floral morphology suggested that P. duckei is a distylous species. However, crossing experiments revealed that it is functionally dioecious. The flowers are actinomorphic, yellowish, produce nectar and a sweet odor, which is more intense in the morning. Anthesis started in the morning between 5.00 and 6.00 AM and extended until dusk, when the corolla tube abscissed. The flowers were visited mostly by bees of the genus Melipona. Pagamea duckei is not agamospermic and thus needs pollen vectors for effective pollination. The results of this study strengthen the idea that, in Pagamea, species with distylous flower morphology are actually functionally dioecious