Formación inicial de los espermatofóros en el testículo del cangrejo Uca uruguayensis (Brachyura: Ocypodidae) / Initial formation of spermatophores in the testicles of the crab Uca uruguayensis (Brachyura: Ocypodidae)

The functional anatomy of the male reproductive system of Uca uruguayensis from Mar Chiquita lagoon, (37º45' S, 57º26' W), Argentina, was known only from optical icroscopy. The present study describes the participation of vas deferens regions in spermatophore formation. A detailed description of the functional morphology of the different regions of the testicular lobes was carried out using both light and scanning electron microscopy. Spermatophore formation begins at the base of the testicular lobe. In most brachyuran species, the spermatophore starts formation when spermatozoa move from the collecting ducts of the testis to the vas deferens. However, in U. uruguayensis observations suggest that the formation of the spermatophore walls occurred in the terminal region of the testis, and that the spermatophore was formed at the junction of the testis and the vas deferens.

La anatomía funcional del sistema reproductor de los machos de Uca uruguayensis de la población de la laguna de Mar Chiquita (37º45' S, 57º26' W), Argentina, ha sido previamente estudiada empleando microscopía óptica. En el presente estudio se demostró la intervención del vaso deferente, en sus distintas regiones, en la formación del espermatóforo y la inclusión del fluido espermático. Se amplía la descripción de la morfología funcional de las regiones de los lóbulos testiculares (empleando también microscopía electrónica de barrido). La formación de los espermatóforos se inicia en la base del lóbulo testicular. El mecanismo descrito hasta el momento para la mayor parte de las especies de braquiuros postula que los espermatóforos comienzan a formarse cuando los espermatozoos pasan de los colectores del testículo al vaso deferente. Nuestras observaciones sugieren sin embargo, que en esta especie la formación de la pared del espermatóforo se inicia en la base de los lóbulos testiculares, y que los espermatóforos están completamente formados en la unión de los testículos y el vaso deferente anterior.

Functional morphology of the hepatopancreas of Palaemonetes argentinus (Crustacea: Decapoda): influence of environmental pollution

We analyzed the morphological and functional state of hepatopancreas in Palaemonetes argentinusfrom two environments with different pesticide concentrations. Los Padres lagoon (Argentina) is an area subjectedto contamination due to the slow exchange of water, the shallow depth and the input of contaminatedwater. Prawns living in this lagoon accumulate high amounts of organochlorine pesticides in their tissues. Hepatopancreas of prawns from Canal 5, an adjacent shallow stream where the amount of pesticides is belowtoxic levels, and from Los Padres lagoon were processed by standard histological techniques with light microscopyand transmission electronic microscopy. At Los Padres lagoon, we found important tissular alterations,such as intertubular infiltration of haemocytes and connective tissue, epithelial retraction in some tubules, anda folded basal lamina. Important necrotic desquamation, with cariolysis, cariorrexis and lack of cellular detailswere also observed. Numerous tubules presented an enlarged and irregular lumen with the epithelium atrophiedor completely absent. In general, the lesions were particularly located in the medullar region of the organ. Atthe ultrastructural level, R and F cells were the most damaged. Both cell types had nuclear retraction, chromatincondensation and cytoplasmic lysis. Some R cells also had dilated mitochondria and numerous lysosomes, and the basal cytoplasm was nearly completely lysed. The hepatopancreas of prawns from Canal 5 did not evidenceany alterations. The histopathological study of the hepatopancreas is a highly sensitive tool to evaluate thephysiological condition of prawns and water quality. Other environmental conditions were similar, so it can beassumed that pollutants were the main cause of organ deterioration.

Analizamos el estado morfológico y funcional del hepatopáncreas de Palaemonetes argentinus de dosambientes con diferentes concentraciones de plaguicidas. La laguna Los Padres (Argentina) es un área sujeta a contaminación debido al lento intercambio del agua, la escasa profundidad y el influjo de agua contaminada. Las gambas acumulan aquí grandes cantidades de plaguicidasorganoclorados en sus tejidos. Los hepatopáncreas de gambas del Canal 5 y de la laguna Los Padres fueronprocesados mediante técnicas histológicas estándar para microscopía óptica y electrónica de transmisión. Loshepatopáncreas de los individuos recolectados en Los Padres tenían alteraciones tisulares importantes, comoinfiltración intertubular de hemocitos y tejido conectivo, retracción epitelial en algunos túbulos y láminas basalesplegadas. También se observó descamación necrótica importante, con cariolisis, cariorrexis y falta de detallescelulares. Vimos muchos túbulos con un lúmen irregular y agrandado, con el epitelio atrofiado o completamenteausente. En general las lesiones se localizaron en la región medular del órgano. Ambos tipos celulares mostraronretracción del núcleo, condensación de la cromatina y ruptura del citoplasma. Algunas células R también teníanmitocondrias y numerosos lisosomas dilatados, y el citoplasma basal casi completamente desintegrado. Nohallamos alteraciones en los hepatopáncreas de gambas deCanal 5. El estudio histopatológico del hepatopáncreas es una herramienta muy apropiada para evaluar la condiciónfisiológica de las gambas y la calidad del agua. Por la semejanza de otras condiciones ambientales, suponemosque los contaminantes fueron la causa principal del deterioro de los órganos.

Morphology and histology of P. argentinus (Crustacea, Decapoda, Caridea) digestive tract

This work describes the morphology and histology of the P. Argentinus digestive tract. The foregut comprises the mouth, oesophagus, and stomach and is lined by a simple cylindrical epithelium overlain by cuticle. There are tegumental glands in the oral region and in the first portion of the oesophagus and of the hindgut. The cardiac stomach is an oval dorsal sac in the cephalothorax and has no calcified structures. The pyloric stomach comprises an upper chamber and a lower gland filter. The filter consists of an outer row of elongated setae and an inner row of dorsally curved setae forming longitudinal channels 16-18 microm wide. The midgut runs from the dorsal chamber of the pyloric stomach to the sixth abdominal somite without caeca. The hindgut runs from the sixth abdominal somite to the ventral anus. The mid-g ut epithelium comprises dominant cylindrical cells and small undifferentiated cells in the first portion. The hindgut wall presents longitudinal folds, conspicuous muscular bundles, and a folded cuticle. The digestive tract of P. argentinus is basically similar to that of most of decapods. The absence of calcified structures in the stomach and the width of the longitudinal channels in the filter are related to the predominantly detritivorous diet.(AU)

Morphology and histology of P. argentinus (Crustacea, Decapoda, Caridea) digestive tract

This work describes the morphology and histology of the P. Argentinus digestive tract. The foregut comprises the mouth, oesophagus, and stomach and is lined by a simple cylindrical epithelium overlain by cuticle. There are tegumental glands in the oral region and in the first portion of the oesophagus and of the hindgut. The cardiac stomach is an oval dorsal sac in the cephalothorax and has no calcified structures. The pyloric stomach comprises an upper chamber and a lower gland filter. The filter consists of an outer row of elongated setae and an inner row of dorsally curved setae forming longitudinal channels 16-18 microm wide. The midgut runs from the dorsal chamber of the pyloric stomach to the sixth abdominal somite without caeca. The hindgut runs from the sixth abdominal somite to the ventral anus. The mid-g ut epithelium comprises dominant cylindrical cells and small undifferentiated cells in the first portion. The hindgut wall presents longitudinal folds, conspicuous muscular bundles, and a folded cuticle. The digestive tract of P. argentinus is basically similar to that of most of decapods. The absence of calcified structures in the stomach and the width of the longitudinal channels in the filter are related to the predominantly detritivorous diet.

Changes in the hepatopancreas histology of Palaemonetes argentinus (Crustacea, Caridea) during moult.

The present work describes the histological changes in the hepatopancreas of Palaemonetes argentinus during the moulting cycle. The hepatopancreas of individuals at different moult stages were dissected and studied using histological techniques. The hepatopancreas in intermoult presents four typical cell types (E, F, R and B) and follows the general plan of the rest of decapods. During early premoult (D1), there is an important secretory activity and many R-cells have several subapical vacuoles and are highly columnar. In early postmoult (A), B-cells are confined to the proximal zone of the tubules. Some of the tubules show a folded basal lamina in late premoult and postmoult. Degenerative desquamation occurs at the proximal zone of the tubules in all the stages, this zone being replenished by mitosis of E cells. Mucopolysaccharides and glycogen reserves are more abundant in premoult than in the rest of the cycle. Cellular height increased in premoult and decreased towards the intermoult, stage of more stability. R-cells are the most abundant, and F-cells do not change significantly through the cycle. The observations suggest that the hepatopancreas of P. argentinus undergoes a significant dynamic and cellular turn over rate in relation to moult.

Changes in the hepatopancreas histology of Palaemonetes argentinus (Crustacea, Caridea) during moult.

The present work describes the histological changes in the hepatopancreas of Palaemonetes argentinus during the moulting cycle. The hepatopancreas of individuals at different moult stages were dissected and studied using histological techniques. The hepatopancreas in intermoult presents four typical cell types (E, F, R and B) and follows the general plan of the rest of decapods. During early premoult (D1), there is an important secretory activity and many R-cells have several subapical vacuoles and are highly columnar. In early postmoult (A), B-cells are confined to the proximal zone of the tubules. Some of the tubules show a folded basal lamina in late premoult and postmoult. Degenerative desquamation occurs at the proximal zone of the tubules in all the stages, this zone being replenished by mitosis of E cells. Mucopolysaccharides and glycogen reserves are more abundant in premoult than in the rest of the cycle. Cellular height increased in premoult and decreased towards the intermoult, stage of more stability. R-cells are the most abundant, and F-cells do not change significantly through the cycle. The observations suggest that the hepatopancreas of P. argentinus undergoes a significant dynamic and cellular turn over rate in relation to moult.

Histology of the hepatopancreas of the freshwater prawn Palaemonetes argentinus (Crustacea, Caridea).

The aim of this study is to describe the histological structure of the hepatopancreas of P. argentinus in intermoult stage in order to provide a baseline for future analysis of its modifications as indicator of environmental stress. Adults at sexual rest of both sexes were collected from Sotelo stream, tributary of Mar Chiquita lagoon, Argentina (38 degrees S 55 degrees W). P. argentinus hepatopancreas was studied by using histological techniques. The hepatopancreas is a bilaterally bilobed brown-yellowish organ. The structure is formed by a mass of blind tubules, with scarce intertubular space. Each tubule consists of a cylindrical epithelial layer surrounded by a basal lamina and myoepithelial cells. Four cellular types were recognized which represent E (embryonic), F (fibrillar), R (resorptive) and B (blisterlike) cells of other decapods. E-cells were found in mitosis and some F-cells had signs of cellular death. B-cells were observed in different phases of holocrine secretion and some groups of desquamated cells appeared at medial and proximal zones, revealing an important cellular turnover rate. According to these observations F, R and B cells are differentiated independently from E-cells.

Histology of the hepatopancreas of the freshwater prawn Palaemonetes argentinus (Crustacea, Caridea).

The aim of this study is to describe the histological structure of the hepatopancreas of P. argentinus in intermoult stage in order to provide a baseline for future analysis of its modifications as indicator of environmental stress. Adults at sexual rest of both sexes were collected from Sotelo stream, tributary of Mar Chiquita lagoon, Argentina (38 degrees S 55 degrees W). P. argentinus hepatopancreas was studied by using histological techniques. The hepatopancreas is a bilaterally bilobed brown-yellowish organ. The structure is formed by a mass of blind tubules, with scarce intertubular space. Each tubule consists of a cylindrical epithelial layer surrounded by a basal lamina and myoepithelial cells. Four cellular types were recognized which represent E (embryonic), F (fibrillar), R (resorptive) and B (blisterlike) cells of other decapods. E-cells were found in mitosis and some F-cells had signs of cellular death. B-cells were observed in different phases of holocrine secretion and some groups of desquamated cells appeared at medial and proximal zones, revealing an important cellular turnover rate. According to these observations F, R and B cells are differentiated independently from E-cells.