Acid and alkaline phosphatase localization in the digestive tract mucosa of the Hemisorubim platyrhynchos.

This cytochemical study investigated the acid and alkaline phosphatase of the digestive tract of Hemisorubim platyrhynchos. Acid phosphatase was detected in the lining epithelium throughout the digestive tract, whereas alkaline phosphatase was only observed in the intestine. In the esophagus, an acid phosphatase reaction occurred in the apical cytoplasm of the epithelial cells and was related to epithelial protection and freeing of superficial cells for sloughing. Similar results were also observed in epithelial cells of gastric epithelium. In the gastric glands, acid phosphatase occurred in lysosomes of the oxynticopeptic cells acting in the macromolecule degradation for use as an energy source, whereas in the vesiculotubular system, its presence could be related to secretion processes. Furthermore, acid phosphatase in the intestine occurred in microvilli and lysosomes of the enterocytes and was correlated to absorption and intracellular digestion. However, no difference was reported among the regions of the intestine. However, alkaline phosphatase reaction revealed a large number of reaction dots in the anterior intestine, with the number decreasing toward the posterior intestine. This enzyme has been related to several functions, highlighting its role in the nutrient absorption primarily in the anterior intestine but also being essential in pH regulation because this is a carnivorous species with many gastric glands with secretions that could damage the intestine.

Morphology and histochemistry of the digestive tract in carnivorous freshwater Hemisorubim platyrhynchos (Siluriformes: Pimelodidae).

The aim of this study was to characterize the morphology and histochemistry of the digestive tract of Hemisorubim platyrhynchos, a freshwater carnivorous catfish found in Neotropical region, using gross anatomy, light microscopy and transmission electron microscopy. This species presented a short and tubular esophagus with thick longitudinal folds. The esophageal mucosa was lined by stratified squamous epithelium containing epithelial cells, club cells and also numerous goblet cells, which secreted acidic and neutral mucins to protect and lubricate the epithelium. The stomach was a J-shaped saccular organ consisting of the cardiac, fundic and pyloric regions. The cardiac and fundic regions contained tubular gastric glands, whereas these glands were absent in the pyloric region. The gastric epithelial cells presented apical secretions that predominantly consisted of neutral mucins. The gastric musculature was, therefore, likely designed for retaining prey and the mechanical preparation of food. The intestine consisted of four regions: anterior, middle, posterior and rectal. The anterior intestine possessed thick folds to increase the surface area for absorption, the middle intestine was coiled and the posterior intestine presented thin folds and a thick musculature. The intestinal epithelium consisted mainly of enterocytes and goblet cells. Enterocytes were columnar cells with a PAS-positive brush border that contained lysosomes in the posterior intestine. Goblet cells were more numerous in the posterior intestine and secreted acidic and neutral mucins important for lubricating and protecting the epithelium. The rectum was lined by columnar epithelium with goblet cells and epithelial cells containing apical acidic and neutral mucins.

Histoarchitectural features of the hepatopancreas of the Amazon River prawn Macrobrachium amazonicum / Histoarquitectura del hepatopáncreas del camarón de la Amazonia Macrobrachium amazonicum

In decapod crustaceans, the digestive gland is concerned with the digestion, absorption of nutrients, the storage of reserves and excretion. The metabolism and the histological and histochemical changes of the hepatopancreas are observed in response to physiological demands as moult, reproduction, digestive process. Thus the hepatopancreas structure should be recognized to provide important morphological information to future studies involving the nutrition requirements of freshwater prawn culture. In this study, second-generation Macrobrachium amazonicum produced from wild broodstock collected in the state of Para in Brazil were used. Thirty adult male and female M. amazonicum were selected and randomly transferred to five experimental units for macroscopic and microscopic studies. The hepatopancreas of M. amazonicum is a large, yellowish-brown, compact organ, which occupies much of the cephalothoracic cavity. It has right and left halves that are enclosed together in a laminar connective tissue capsule, and at the same time they are separated by an interstitial connective tissue. The two halves are thereby called the right and left hepatopancreatic lobes. The principal tubule gives rise to four secondary tubules at each hepatopancreatic lobe. The morphological and functional unit consists of a blind-ended hepatopancreatic tubule, considered in the present study as the hepatopancreatic lobule. Each hepatopancreatic tubule can be subdivided into distal, medial and proximal zones. The hepatopancreatic tubule is lined by a pseudostratified epithelium that consists of five different cell types, which include the E-cell (embryonic), F-cell (fibrillar), B-cell (blister-like), R-cell (resorptive) and M-cell (midgut or basal). It is important to emphasize that the function of each cell type in the hepatopancreas during the digestive cycle is not yet established for decapods.

La glándula digestiva en los crustáceos decápodos asume las funciones de digestión, absorción de nutrientes, almacenamiento de las reservas energéticas y excreción de metabolitos. El metabolismo y las alteraciones histológicas e histoquímicas son observados como respuesta a necesidades fisiológicas, tales como: muda, reproducción y procesos digestivos. Por lo tanto, se requiere conocer la estructura histológica del hepatopancreas con el fin de reunir información morfológica para futuros estudios que consideren las necesidades nutricionales para el cultivo de los camarones de agua dulce. Fueran utilizados 30 animales, machos y hembras de Macrobrachium amazonicum, producidos a partir de reproductores colectados en el Estado de Para, Brasil. Las observaciones macro y microscópicas permitieron concluir que el hepatopancreas del M. amazonicum es un órgano grande y compacto de color amarillo tendiendo a marrón, que ocupa la mayor parte de la cavidad céfalo-torácica. El órgano presenta dos mitades, derecha y izquierda, las cuales están envueltas por una cápsula de tejido conjuntivo, y al mismo tiempo, separadas por tejido conectivo intersticial. Las dos mitades del órgano son identificadas como lobos derecho e izquierdo. Cada lobo presenta un túbulo principal que origina cuatro túbulos secundarios. Por lo tanto, la unidad morfofuncional del hepatopancreas consiste en un túbulo hepatopancreático de fondo ciego, considerado en esta investigación como lóbulo hepatopancreático. Cada lóbulo hepatopancreático puede ser dividido en 3 regiones: distal, media y proximal, y en su totalidad, se observa revestido por epitelio seudo estratificado que reúne cinco tipos celulares: célula E (embrionaria), célula F (fibrilar), célula B (globosa), célula R (reabsortiva) y célula M (basal). Es importante enfatizar que la función de cada tipo celular del hepatopancreas no está todavía aclarada para los decápodos.

Estrutura microscópica do rim de cobaia (Cavia porcellus, L.) / The microscopic structure of guinea pig kidney (Cavia porcellus, L.)

A estrutura microscópica do rim de cobaia é caracterizada por disposiçäo predominantemente centralizadas dos principais componentes dos néfrons, compreendendo os corpúsculos renais e os túbulos contorcidos proximais e distais, localizados na parte intermediária do córtex renal. Os seguimentos espessos e delgados das alças do néfron se localizam na medula renal, a diferentes alturas. Os coletores renais retos se observam no córtex, medula e papilas renais, sendo mais conspicuamente observados na papila. As células epiteliais, que revestem os túbulos contorcidos proximais e distais, apresentam características ultra-estruturais, que as associam diretamente aos processos citofisiológicos de absorçäo de água, íons salinos e solutos

Ultraestructure of the cortical segments of the nephron in guinea pig: cavia porcellus

Los segmentos corticales del nefron de cavia porcellus, están formados por glomérulos; tubos contorneados proximal y distal. Las capas parietal y visceral de la cápsula de Bowman son fácilmente identificables en el microscopio electrónico de transmisión. Los podocitos pueden estar relacionados con el coeficiente de ultrafiltración urinario y regulación de la filtración glomerular. Las células mesangiales presentan una posible función de secreción de renina, que actúa en la regulación de la presión arterial. Las células epiteliales que revisten los tubos contorneados proximales, presentan características ultraestructurales que reflejan la resorción de agua, sales y electrolitos