Systematization, distribution, and territories of the caudal cerebral artery on the surface of the brain in nutria (Myocastor coypus) / Sistematização, distribuição e territórios da artéria cerebral caudal na superfície do cérebro em Nutria (Myocastor coypus)

The nutria (Myocastor coypus) is a medium-sized, semi-aquatic rodent valued by the skin and meat industry. This study aimed to describe and systematize the caudal cerebral artery on the brain surface in nutria, establishing a standard model and its main variations in this species. The thirty animals used were euthanized according to animal welfare rules. The vessels were filled with latex stained with red pigment and the samples were fixed in formaldehyde. In nutria, the brain was vascularized by the vertebral basilar system. The terminal branches of the basilar artery originated the rostral cerebellar, caudal cerebral, rostral choroidal and middle cerebral arteries, and its terminal branch, the rostral cerebral artery. The terminal branch of the basilar artery projected the caudal cerebral artery, which is usually a single medium-caliber vessel, into the transverse fissure of the brain. The caudal cerebral artery was presented as a single (66.7% of the cases to the right and 76.7% to the left) and double vessel (33.3% of the cases to the right and 23.3% to the left). It originated the rostral mesencephalic artery, the proximal component, and the caudal inter-hemispheric artery. The terminal branches of the rostral and caudal tectal mesencephalic arteries formed a typical anastomotic network. The caudal inter-hemispheric artery emitted central branches, the caudal choroidal artery, hemispherical occipital arteries, rostral tectal mesencephalic branches and distal components, and anastomosed "in osculum" with the terminal branches of the rostral inter-hemispheric artery. The caudal choroidal artery anastomosed with the rostral choroidal artery, where it branched out on the thalamic mass, vascularizing all diencephalic structures and the hippocampus. The caudal cerebral artery and its terminal branches anastomosed with the terminal branches of the rostral and middle cerebral arteries in a restricted region of the caudal pole of the cerebral hemisphere. The vascularization area of the caudal cerebral artery and its central branches in the paleopallial of the piriform lobe is extremely restricted, caudomedially.(AU)

A nutria (Myocastor coypus) é um roedor semi-aquático de tamanho mediano, apreciado na indústria de peles e carne. Este trabalho tem por objetivo descrever e sistematizar a artéria cerebral caudal na superfície do cérebro em nutria, estabelecendo um modelo padrão e suas principais variações e territórios nesta espécie. Os trinta animais utilizados foram eutanasiados segundo as regras de bem-estar animal, os vasos foram preenchidos com látex, corado em vermelho e as peças foram fixadas em formoldeído. O cérebro foi vascularizado exclusivamente pelo sistema vértebro-basilar. Os ramos terminais da artéria basilar originaram as artérias cerebelar rostral, cerebral caudal, corióidea rostral, cerebral média e seu ramo terminal, a artéria cerebral rostral. O ramo terminal da artéria basilar lançou a artéria cerebral caudal, um vaso normalmente único, de médio calibre, para o interior da fissura transversa do cérebro. A artéria cerebral caudal foi um vaso único em 66,7% à direita e em 76,7% à esquerda e mostrou-se dupla em 33,3% à direita e em 23,3% à esquerda. Ela lançou a artéria tectal mesencefálica rostral, componente proximal e a artéria inter-hemisférica caudal. Os ramos terminais das artérias tectais mesencefálicas, rostral e caudal, formavam uma rede anastomótica típica. A artéria inter-hemisférica caudal lançou ramos centrais, a artéria corióidea caudal, as artérias hemisféricas occipitais, os ramos tectais mesencefálicos rostrais, componentes distais e anastomosou-se "em ósculo" com o ramo terminal da artéria inter-hemisférica rostral. A artéria corióidea caudal anastomosava-se com a artéria corióidea rostral, onde ramificavam-se sobre a massa talâmica, vascularizando todas as estruturas do diencéfalo e hipocampo. A artéria cerebral caudal com seus ramos terminais apresenta anastomoses com os ramos terminais das artérias cerebrais rostral e média em uma região restrita do pólo caudal do hemisfério cerebral. A área de vascularização da artéria cerebral caudal com seus ramos centrais no páleo-palio do lobo piriforme é extremamente restrita, caudo-medialmente ao mesmo.(AU)

Ectoparasites from some Myocastor coypus (Molina, 1782) populations (Coypus or Nutria) in Argentina / Ectoparasitas de algumas populações de Myocastor coypus (Molina, 1782) (Coypus ou Nutria) na Argentina

Abstract The occurrence of ectoparasites in wild nutria is poorly understood. Fifty-five livetrapped wild nutria (Myocastor coypus) from its indigenous region were examined for ectoparasites after capture from December 2013 to December 2014. The captures came from the Buenos Aires Province, by far the area of the country most densely populated by nutria, characterized as a temperate grassland, which are prime areas for sustained agriculture. Only one species of chewing lice (Pitrufquenia coypus, Marelli, 1932), one flea (Nosopsyllus fasciatus, Bosc, 1800) and one tick (Rhipicephalus sanguineus, Latreille, 1806) were collected. Fourteen percent of the animals were infested and P.coypus, an obligate parasite of the nutria, which was the most prevalent ectoparasite. N. fasciatus and R. sanguineus occurrence remains controversial as they may or may not be some accidental host species. To our knowledge, this is the first comprehensive and systematic survey of ectoparasites in wild nutria from the southern hemisphere, the indigenous region of this species.

Resumo A ocorrência de ectoparasitas em nutria selvagem é pouco compreendido. Cinquenta e cinco nutria selvagem capturadas (Myocastor coypus) de sua região indígena foram examinados para os ectoparasitas após até captura a partir de dezembro de 2013 a dezembro de 2014. As capturas ocorreram no estado de Buenos Aires, a área mais densamente povoada do país por nutria, caraterizada como uma pastagem temperada, que se tornou área principal para a agricultura sustentável. Uma espécie de piolhos de mastigação (Pitrufquenia coypus, Marelli, 1932), uma pulga (Nosopsyllus fasciatus, Bosc, 1800) e um carrapato (Rhipicephalus sanguineus, Latreille, 1806) foram recolhidos. Catorze por cento dos animais foram infestadas pelo P.coypus, um parasita obrigatório do nutria, sendo o ectoparasita mais prevalente. A ocorrência de N. fasciatus e R. sanguineus continua controversa, pois podem ou não ser algumas espécies hospedeiras acidentais. Para nosso conhecimento, este é o primeiro estudo abrangente e sistemático de ectoparasitas em nutria selvagem do hemisfério sul, a região indígena desta espécie.

A Case of Fascioliasis in A Wild Nutria, Myocastor coypus, in Republic of Korea

A total of 44 adult or juvenile nutrias were necropsied for disease survey. A large nodule was found in the liver of a nutria. The histopathological specimen of the hepatic nodule was microscopically examined, and sectional worms were found in the bile duct. The worms showed a tegument with spines, highly branches of vitelline glands and intestine. Finally, we histopathologically confirmed fascioliasis in a wild nutria. In the present study, a case of fascioliasis in a wild nutria is first confirmed in Korea.

Observaciones sobre la Morfología del Oviducto del Coipo (Myocastor coypus) / Observations on Oviduct Morphology of the Coypu (Myocastor coypus)

Se efectuaron los análisis anatómico e histoarquitectónico del oviducto del coipo (Myocastor coypus) en la madurez sexual. Se trabajó con 34 oviductos que fueron segmentados en infundíbulo, ampolla, unión ámpulo-ístmica, istmo cefálico, medio y caudal y procesados con técnicas histológicas de rutina. Los oviductos se observaron como órganos tubulares y tortuosos, con amplia superficie infundibular, marcada flexura en la unión con los cuernos uterinos y el desarrollo de un colículo en la unión útero-tubárica. La mucosa presentó plegamientos que disminuyeron en número, grado de ramificación y altura desde la ampolla hasta los comienzos de la unión útero-tubárica. El epitelio de revestimiento estuvo compuesto por células ciliadas y células secretoras. En el infundíbulo y el istmo fue cilíndrico simple, en tanto que en la ampolla fue seudoestratificado cilíndrico. En las regiones caudales del istmo se observaron criptas revestidas por un epitelio cilíndrico de aspecto secretor. La lámina propia fue de tejido conectivo laxo y muy vascularizado. La túnica muscular incrementó su grosor y complejidad desde el infundíbulo a la unión útero-tubárica.

Anatomical and histoachitectonic analyses of coypu (Myocastor coypus) oviduct were performed at sexual maturity. Thirty-four oviducts were segmented into: infundibulum, ampulla, cephalic istmus, middle and caudal. Routine histological techniques were used. Oviducts were observed as tubular and tortuous organs with a wide infundibular surface, a pronounce flexure at junction of the uterine horns and with a colliculus at the utero-tubaric junction. The oviductal wall was composed of the mucosal, muscular and serosal tunics. The mucosal tunic showed foldings that diminished in number, ramification and height from the ampulla to the beginning of the utero-tubaric junction. The lining epithelium was composed of ciliated cells as well as secretory cells. In the infundibulum and isthmus, it was simple and cylindrical, while in the ampoule it was cylindrical pseudo-stratified. In the caudal regions of the isthmus, crypts covered by a cylindrical epithelium with secretroy aspect were observed. The lamina propria was composed of highly vascularized lax connective tissue. The muscular tunic increased its thickness and complexity from the infundibulum to the utero-tubaric junction.

Reproductive ecology of coypu (Myocastor coypus Molina, 1782) in the Middle Delta of the Paraná River, Argentina / Ecología reproductiva do coipo (Myocastor coypus) no Delta Meio do Río Paraná (Entre Ríos. Argentina)

The objective of this study was to estimate and compare some important reproductive parameters of Myocastor coypus over time (June 2006-May 2008), in wetlands of the Middle Delta of the Paraná River (MD) Entre Ríos province, R. Argentina. Within the original coypu distribution range, the MD is among the areas of highest habitat suitability for the species. Coypus were captured and the following reproductive parameters were estimated on a monthly, seasonal and annual basis: pregnancy rate (PR), litter size (LS), gross productivity (GP) and annual production (AP). Statistical non-parametric tests were used for comparisons. Additionally, the expected birth date of each embryo and fetus was estimated by assigning it to a developmental stage category and considering the gestation period of the species. All the parameters showed high values and PR and LS differed significantly between the dry (2006) and humid years (2007). Two peaks of birth were detected, one in spring and another one in mid-autumn. The implications of these results for ensuring the sustainable management of this rodent are discussed.

O objetivo deste trabalho é a descripção e comparação ao longo do tempo (junho 2006 – maio 2008), de diversos parámetros da ecologia reprodutiva de Myocastor coypus nas terras úmidas do Delta Meio do Río Paraná (DM), una das zonas de maior aptidão de hábitat para a espécie dentro da sua área de distribuição original. Com base em capturas de exemplares estimaram-se en forma mensal, sazonal y anual, a taxa de prenhez (TP); o tamanho da camada (TC), a produtividade bruta (PB) e a produção anual (PA) e foram realizadas as comparações correspondentes mediante provas estatísticas não paramétricas. Alem disso, com base no estádio de desenvolvimento dos fetos y embriões observados, levando em consideração a duração do período de gestação, estimou-se quais teriam sido as datas de nascimento mais prováveis. Observaram-se valores relativamente altos para todos os parámetros e diferenças significativas entre as TP y os TC de anos secos (2006) e anos úmidos (2007). Também foram detectados dois picos de parição, um em plena primavera e o outro a meados do outono. Discutem-se as implicâncias destes resultados para assegurar o manejo sustentável do coipo, o principal recurso de fauna silvestre argentina.

Strongyloides myopotami (Secernentea: Strongyloididae) from the Intestine of Feral Nutrias (Myocastor coypus) in Korea

Surveys on helminthic fauna of the nutria, Myocastor coypus, have seldom been performed in the Republic of Korea. In the present study, we describe Strongyloides myopotami (Secernentea: Strongyloididae) recovered from the small intestine of feral nutrias. Total 10 adult nutrias were captured in a wetland area in Gimhae-si (City), Gyeongsangnam-do (Province) in April 2013. They were transported to our laboratory, euthanized with ether, and necropsied. About 1,300 nematode specimens were recovered from 10 nutrias, and some of them were morphologically observed by light and scanning electron microscopies. They were 3.7-4.7 (4.0+/-0.36) mm in length, 0.03-0.04 (0.033) mm in width. The worm dimension and other morphological characters, including prominent lips of the vulva, blunted conical tail, straight type of the ovary, and 8-chambered stoma, were all consistent with S. myopotami. This nematode fauna is reported for the first time in Korea.

Ramos colaterais parietais e terminais da aorta abdominal em Myocastor coypus (nutria) / Terminal and parietal colateral branches of the abdominal aorta in Myocastor coypus (nutria)

Neste estudo, utilizaram-se 30 nutrias, 15 fêmeas e 15 machos, com o sistema arterial aórtico-abdominal preenchido com látex 603, pigmentado em vermelho, e fixado em uma solução aquosa de formaldeído a 20 por cento. A aorta abdominal emitiu de sua superfície dorsal de 6 a 8 artérias lombares únicas. Das artérias renais, direita e esquerda, originaram-se as artérias frênico-abdominal para irrigar parte do diafragma e da parede abdominal lateral cranial. A aorta abdominal lançou dorsalmente, a artéria sacral mediana, cranialmente a sua bifurcação em artérias ilíacas comuns. As artérias ilíacas comuns, ramos terminais da aorta abdominal, originaram as artérias ilíacas interna e externa. A artéria ilíaca interna distribuiu-se nas vísceras da cavidade pélvica. A artéria ilíaca externa emitiu uma artéria umbilical e, antes de alcançar o anel femoral, lançou a artéria circunflexa ilíaca profunda para a parede abdominal lateral, em seus dois terços caudais. A artéria ilíaca externa lançou o tronco pudendo-epigástrico, que originou a artéria epigástrica caudal, para a parede abdominal ventral e a artéria pudenda externa, que saiu pelo canal inguinal, para irrigar a genitália externa. Os ramos parietais diretos da aorta abdominal foram as artérias lombares e a artéria sacral mediana, enquanto as artérias frênico-abdominal, circunflexa ilíaca profunda e epigástrica caudal, foram ramos colaterais parietais indiretos. Os ramos terminais da artéria aorta abdominal foram as artérias ilíacas comuns com seus ramos, as artérias ilíacas interna e externa.

For this study it was used 30 nutria, 15 females and 15 males, with its abdominal aorta system full filled with latex 603, stained in red, and fixed in an aqueous solution of formaldehyde 20 percent. The abdominal aorta emitted from its dorsal surface 6 to 8 single lumbar arteries. From the renal arteries, left and right, it has been originated the phrenicoabdominal arteries, in order to irrigate part of the diaphragm and the cranial lateral abdominal walls. The abdominal aorta emitted, dorsally, the median sacral artery, cranially to its bifurcation into the common iliac arteries. These common iliac arteries, terminal branches of the aorta, originate the internal and external iliac arteries. The internal iliac artery was distributed along the pelvic cavity viscera. The external iliac artery emitted an umbilical artery and, before reaching the inguinal ring, emitted the deep circunflex iliac artery to 2/3 of the caudal lateral abdominal wall. The external iliac artery emitted the pudendoepigastric trunk, wich has originated the caudal epigastric artery, to the ventral abdominal wall, and the external pudendal artery, wich passed through the inguinal ring to irrigate the external genital. The direct parietal branches of the abdominal aorta were the lumbar arteries and the median sacral artery, while the phrenicoabdominal arteries, deep circunflex iliac and the caudal epigastric artery were indirect colateral parietal branches. The terminal branches of the abdominal aorta were the common iliac arteries with its branches, the internal and external iliac arteries.

Anatomical Description of the Liver, Hepatic Ligaments and Omenta in the Coypu (Myocastor coypus) / Descripción Anatómica del Hígado, Ligamentos hepáticos y Omentos en el Coipo (Myocastor coypus)

The objective of this work is to give a complementary description of the hepatic lobulation, the hepatic ligaments and the omenta of the nutria. Thirty nutrias were studied by gross dissection. The liver of the nutria was divided into six lobules as follows: left lateral, left medial, quadrate, right medial, right lateral, and caudate lobes. The caudate lobe was divided into a papillary and a caudate process. A whole falciform ligament, extending as far as the navel, was found in all animals. This one was the only ligament that contained fat in between its sheets, and it was abundant in the umbilical part. The left triangular ligament had two parts. One of them was attached to the left lateral lobe of the liver and the other one to the left medial lobe. The right triangular ligament also was double. The lateral triangular ligaments where larger than the medial ones. The hepatorenal ligament it was attached to the right kidney and its ventral free border measured 3.0 cm. The coronary ligament was always relatively well marked and was continuous with all the previous ligaments. The omenta were similar to those described for the rabbit but had more fat. The greater omentum united with the left sheet of the mesoduodenum and to the ascending mesocolon.

El objetivo de este trabajo es complementar las descripciones de la lobulación hepática, los ligamentos hepáticos y los omentos de la nutria. Treinta nutrias fueron estudiadas mediante disección simple. El hígado de la nutria estaba dividido en seis lóbulos: lóbulos lateral izquierdo, medial izquierdo, cuadrado, medial derecho, lateral derecho y caudado. El lóbulo caudado estaba dividido en proceso papilar y proceso caudado. Un ligamento falciforme completo, extendido hasta el ombligo, fue hallado en todos los animales. Este era el único ligamento que tenía grasa entre sus hojas, la cual era abundante en la parte umbilical. El hgamento triangular izquierdo estaba compuesto por dos partes. Una parte se fijaba al lóbulo lateral izquierdo y la otra al lóbulo medial izquierdo del hígado. El hgamento triangular derecho también era doble. Los hgamentos triangulares laterales eran más grandes que los mediales. El hgamento hepatorrenal estaba unido al riñon derecho y medía 3,0 cm en su borde hbre ventral. El ligamento coronario era siempre relativamente marcado y se continuaba con todos los ligamentos anteriores. Los omentos eran similares a los descritos para el conejo pero más cargados de grasa. El omento mayor se unía a la hoja izquierda del mesoduodeno y al mesocolon ascendente.

External Morphological Characterization of 60-Days Gestation Myocastor coypus (Coypu) Fetuses / Caracterización de la Morfología Externa de Fetos de 60 Días de Gestación de Myocastor coypus (Coipo)

The main objective of this work was to carry out the external morphology characterization of 60-days gestation Myocastor coypus (coypu) fetuses since this stage could be considered a crucial point in the prenatal development in this species. Fourteen fetuses out of three litter were analised. Gestational sacs weighing 3.81 ± 0.27 g showed an elliptical shape with the larger axis along the direction of the uterus. The average weight of fetuses was 1.13 ± 0.19 g, the head-to-tail lenght was 1.99 ± 0.87 cm, the cephalic lenght was 1.01 ± 0.37 cm, and the biparietal diameter was 0.63 ± 0.06 cm. Specimens showed differentiation in corporeal, limbs and tail regions; also showed interdigital membranes, well defined optical vesicles and lateral ear lobe sprouts. Comparative analysis of coypu fetuses and equivalent stages of other mammal species will allow to establish similitudes and differences that would permit to mark particularities in the ontogeny of Myocastor coypus.

El objetivo de este trabajo fue efectuar la caracterización de la morfología externa de fetos de 60 días de gestación en Myocastor coypus (coipo), ya que éstos pueden ser considerados como un punto de inflexión en el desarrollo prenatal de la especie. Se analizaron 14 fetos provenientes de tres camadas. Los sacos gestacionales, cuyo peso fue de 3.81 ± 0.27 g, mostraron forma elíptica, con su diámetro mayor orientado en paralelo con la dirección de los hemiúteros. El peso medio de los fetos fue de 1.13 ± 0.19 grs, con una longitud céfalo-caudal de 1.99 ± 0.87 cm, longitud cefálica de 1.01 ± 0.37 cm y un diámetro biparietal de 0.63 ± 0.06 cm. Los especímenes mostraron diferenciación de regiones corporales, extremidades y cola, membranas interdigitales en los miembros posteriores, vesículas ópticas bien definidas y esbozos de pabellones auriculares en posición lateral. El análisis comparativo de los fetos de coipo con estadios equivalentes de otros mamíferos, permitió determinar similitudes y también diferencias que indicarían particularidades de la especie.