Anatomy of the visceral cavity of Eugerresmexicanus (Teleostei: Gerreidae) / Anatomía de la cavidad visceral de la mojarra mexicana Eugerres mexicanus (Teleostei: Gerreidae)

Introduction. The visceral cavity of teleostean fishes contains the kidneys, digestive tube and annexed glands, gas bladder, gonads, and spleen. Objective: To analyze and describe the anatomic relationships of the organs of the visceral cavity of the Mexican mojarra, Eugerres mexicanus. Methods: By means of dissections, we analyzed, described and illustrated the splanchnology of the visceral cavity of 10 adult specimens from the State of Chiapas, Mexico. Results: The visceral cavity is delimited by the precaudal vertebrae, the scapular and pelvic girdles, the pleural ribs, the first anal pterygiophore and several myotomes. Both kidneys, with extraperitoneal character are partially fused to each other, and contact the neurocranium, the precaudal vertebrae, and the gas bladder. The digestive tube does not present a stomach nor pyloric caeca, and it is 1.3 the standard length of the fish. The liver has two short right lobes. Both ovaries and testes are wide and reach the liver. The spleen is ovoid and is located on the left side of the duodenum. The gas bladder has two anterior lobes, its posterior end is in direct contact with the floor of the visceral cavity, and contain the urinary bladder. Discussion: The organization of the organs in the visceral cavity is in the anatomical pattern of the teleostean fishes, however, the organ that shows the highest number of special characters is the gas bladder, which as in other species of Eugerres is large and shows two notable anterior lobes, reinforced by epipleural ribs. Compared with other species of Eugerres, the Mexican mojarra shows, as exclusive characters: a) the union of the posterior end of the gas bladder with the floor of the visceral cavity, and, b) the location of the urinary bladder within the gas bladder.

Introducción: La cavidad visceral de los peces teleósteos contiene a los riñones, el tubo digestivo con sus glándulas anexas, la vejiga gaseosa, las gónadas y el bazo. Objetivo: Analizar y describir las relaciones topográficas de los órganos de la cavidad visceral de la "mojarra mexicana" Eugerres mexicanus. Metodología: Mediante disecciones se analizó y describió la esplacnología de la cavidad visceral de 10 ejemplares adultos recolectados en el estado de Chiapas, México. Resultados: La cavidad visceral, está delimitada por las vértebras precaudales, las cinturas, las costillas pleurales, el primer pterigióforo anal y varios miotomos. Los riñones, los cuales son extraperitoneales, están parcialmente fusionados entre sí. El sistema digestivo carece de estómago y ciegos pilóricos y su longitud corresponde a 1.3 de la longitud patrón. El hígado tiene dos lóbulos derechos. Las gónadas maduras son amplias. La vejiga gaseosa desarrolla dos lóbulos anteriores y su extremo posterior se une al piso de la cavidad visceral, e incluye a la vejiga urinaria. Discusión: La organización de la cavidad visceral y sus órganos corresponde al patrón morfológico de los peces teleósteos, siendo la vejiga gaseosa el órgano que muestra el mayor número de caracteres especiales, como los lóbulos anteriores, la unión de su extremo inferior al piso de la cavidad visceral y la ubicación de la vejiga urinaria en su interior. Estos dos últimos caracteres la distinguen de otras especies del género Eugerres.

Neonatal expression of amh, sox9 and sf-1 mRNA in Caiman latirostris and effects of in ovo exposure to endocrine disrupting chemicals.

Caiman latirostris is a reptilian species that exhibits temperature-dependent sex determination (TSD). Male-to-female sex reversal can be achieved after in ovo estrogen/xenoestrogen exposure. This is known as hormone-dependent sex determination (HSD). The amh, sox9 and sf-1 genes are involved in sex determination, sex differentiation, and steroidogenesis. The aims of this study were: (a) to establish the expression patterns of amh, sox9 and sf-1 mRNA in the gonad-adrenal-mesonephros (GAM) complexes of neonatal TSD-male and TSD-female caimans, (b) to compare the expression of these genes between TSD-females and HSD-females (born from E2-exposed eggs incubated at the male-producing temperature) and (c) to evaluate whether in ovo exposure to a low dose of E2 or bisphenol A (BPA) or to a high dose of endosulfan (END) modifies amh, sox9 or sf-1 mRNA expressions in neonatal males. The mRNA expressions of amh, sox9 and sf-1 in GAM complexes from TSD-males and TSD-females and from HSD-females were quantitatively compared by RT-PCR. A sexually dimorphic pattern of amh and sox9 mRNA expression was found, with a higher expression in TSD-males than in TSD-females. sf-1 mRNA did not differ between TSD-males and TSD-females. HSD-females exhibited a higher expression of sox9 than TSD-females. In males, increased mRNA expression of sex-determining genes was observed after in ovo exposure to END. E2 decreased sox9 but increased sf-1 mRNA expression. Changes induced by BPA were evident although not significant. These results provide new insights into the potential mechanisms that lead to the gonadal histo-functional alterations observed in caimans exposed to contaminated environments.

Morphology and dissection technique of the kidney of the grey snapper lutjanus griseus (teleostei: lutjanidae) / Morfología y técnica de disección del riñón del pargo gris lutjanus griseus (teleostei: lutjanidae)

In order to describe the morphology of the kidney and implement its dissection technique, specimens of the grey snapper Lutjanus griseus were analyzed. The morphology of the kidney fits with the structural pattern of the higher teleosts, consisting of a large fusion of the right kidney with the left, with the exception of the anterior renal lobes. Both anterior renal lobes are separated by the retractores dorsales muscles and by the anchorage of the gas bladder to the vertebrae. Some cranial and spinal nerves, as well as ribs, blood vessels, the Baudelot's ligament, the sinus venosus of the heart, the precaudal vertebrae, and the gas bladder mark the surface of the kidney. The archinephric ducts are connected with the urinary bladder, from which the common urinary and urogenital leaves.

Con el objeto de describir la morfología del riñón y de implementar su técnica de disección, se analizaron ejemplares del pargo gris Lutjanus griseus. La morfología del riñón corresponde al patrón estructural de los teleósteos superiores, consistiendo en una amplia fusión del riñón derecho con el izquierdo, con excepción de los lóbulos renales anteriores. Ambos lóbulos renales anteriores están separados por los músculos retractores dorsales y por el anclaje de la vejiga gaseosa a las vértebras. Algunas estructuras marcan la superficie del riñón, como algunos de los nervios craneales y espinales, las costillas, vasos sanguíneos, el ligamento de Baudelot, el seno venoso del corazón, las vértebras precaudales y la vejiga gaseosa. Los conductos arquinéfricos se conectan a la vesícula urinaria, desde la cual sale el conducto urinario común.