Karina Simões

Myoarchitecture and vasculature of the heart ventricle in some freshwater teleosts

The morphological characteristics of the ventricular myocardium and of coronary vascularization were studied in three freshwater teleost species, Piaractus mesopotamicus, Colossoma macropomum and Clarias gariepinus (African catfish), by correlating their ventricular shapes and swimming habits. In Piaractus mesopotamicus and Colossoma macropomum, species with highly active swimming habits, the cardiac ventricle showed a pyramidal shape and a richly vascularized myocardium consisting of an outer compact layer and inner spongy layer. In Clarias gariepinus, a less active species, we observed a saccular ventricle with a mixed myocardium and coronary arteries, in contrast to the ventricular structure of other species described in the literature.

Vas Deferens Surface Epithelium of Agouti paca: Fine Structural Features

El epitelio que recubre la luz del conducto deferente de la laca (Agouti paca), un roedor silvestre de Sudamerica, esta formado por celulas principales (P) y basales (B), en donde las celulas principales estan asociadas a los procesos de endocitosis y secrecion, teniendo una base en su caracteristica ultraestructural citoplasmatica. Las celulas principales de los vasos deferentes del epitelio se caracteriza principalmente por la presencia de vesiculas con variadas formas, tamanos y contenido interior en su citoplasma apical produciendo pequenas invaginaciones y pequenas vesiculas palidas ubicadas continuas al borde en cepillo de las microveilosidades apicales. Ademas, fueron observados, vesiculas de superficie lisa y vesiculas de gran tamano; organos multivesiculares, endosomas y lisosomas. Tambien se observo la presencia de un aparato secretor apocrino, con expansiones citoplasmaticas apicales que se protruyen en el compartimiento luminar del conducto deferente. Celulas basales aplanadas, sin contacto con la superficie luminal, se encuentran junto a la membrana basal del conducto, las que no presentan caracteristicas ultraestructurales especiales.

Variabilidade sazonal no ducto epididimário de codorna doméstica: observações morfológicas

Small but expressive variability was noted on the epididymidis duct (ED) of domestic quail along the year, with more evidence in autumn of the quiescent phase of the annual testis cycle in this species. Spring features of ED had a general similar pattern in summer and winter. They were characterized by enlargement of epididymis tubule, storage of spermatozoa into the luminal compartment and presence of mitochondria, ER lamellae, several variable vesicles, and lysosomes localized mainly on the apical cytoplasm of principal cells (P) of the epididymal epithelium. These P cells features indicated a process of endocytosis and perhaps protein secretion. Autumn quiescence was marked by a convolute pattern of the epididymis tubule, lacking of spermatozoa and small amount of exfoliate heterogeneous material inside the luminal compartment at light microscopy. Ultrastructural degenerative features mainly apical cytoplasmic debris were seen in the supranuclear cytoplasm of lining P cells.

Características regionais sobre a ultra-estrutura das células principais do epitélio do ducto epididimal de Agouti paca

As celulas principais (P) do epitelio de revestimento do epididimo de paca foram relacionadas com processos citofisiologicos de endocitoses do tipo adsortiva e de fase fluida, respectivamente, aparentemente realizando tambem secrecao apocrina. Essas funcoes foram propostas embasando-se em caracteristicas de ultra-estrutura das celulas P, em cujos citoplasma observaram-se um expressivo numero de vesiculas, com diferentes formas, tamanhos e presenca de conteudo internalizado em algumas das vesiculas revestidas por endomembranas, ocorrendo ainda caveolas e vesiculas diminutas localizadas junto a borda apical de microvilos. Ademais, observaram-se vesiculas grandes e revestidas e/ou com superficies lisas; endossomos, e lisossomos de localizacao predominantemente apical. Uma via de secrecao apocrina foi sugerida com base na ocorrencia de expansoes (protrusoes), citoplasmaticas intraluminais nas celulas P.

Structure and vascularization of the ventricular myocardium of Piaractus mesopotamicus and Clarias gariepinus (Teleostei)

The structural characteristics of the ventricular myocardium and the arterial distribution of the ventricular wall were studied in two freshwater teleost fish species (Piaractus mesopotamicus and Clarias gariepinus). The ventricular myocardium consists of two distinct layers, an external compact layer and an internal spongy layer. In Piaractus mesopotamicus the compact layer contains fibres with an external longitudinal arrangement and an internal circular arrangement. The arterial vascularization of the compact layer is provided by subepicardial vessels and their ramifications in both species.

Light microscope observations on the epididymis of paca (Agouti paca)

The features of paca epididymis, based on its appearance in light microscope, is described in this paper. The cellular population of the epithelial lining comprises principal cells, basal cells, apical cells, narrows cells, and hallo cells. The epididymis is divided in five distinct and continuous regions, Zone I, or initial segment, and zone II, are both localized into the head. Zone III comprises the distal head and all the body. Zones IV and V are restricted to the tail, in the proximal and distal cauda epididymis respectively. Each zone can be readily distinguished on the basis of morphological characteristics. The height of epididymal epithelium is greater in zone I. There is a progressive increase in the diameter of the tubular lumen through the different areas, with the maximum in the zone V. The presence of a high epithelium, and the virtual absence of sperm in zone I suggest fast transit of spermatozoa in this region. Zone V comprises the distal tail, has smaller epithelial lining, greater luminal diameter, shorter stereocilia than the other zones, and contains spermatozoa packed inside the lumen, that characterizes this zone as a place of sperm storage. The findings are compared with other reports in rodents and other domestic animals, to contribute to the understanding of epididymal morphophysiology.

Características morfológicas do miocárdio ventricular de Tambaqui (Colossoma macropomun; Characidae, Cuvier, 1818)

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.