Glycan expression as a tool for a deeper understanding of a reproductive gland in a skate of economic importance.

Atlantoraja platana is an oviparous skate endemic to the south-west Atlantic Ocean, and is one of the skate species most exploited by local industrial bottom trawl fisheries. Oviparous elasmobranchs encapsulate their eggs in complex egg cases produced by the oviductal gland (OG). This organ is exclusively present in these fishes and comprises four distinct zones: club, baffle, papillary and terminal. The relative size and structural complexity of these zones correlate with mode of reproduction. Glycans are known to play major roles in reproduction so their distribution in each zone of the OG could explain the functional multiplicity of the gland in skates, but this topic has not been previously investigated. In this study, morphological, histochemical and lectin-histochemical analysis revealed various novel aspects of A. platana's OG. The club, papillary and terminal zones positively stained for periodic acid Schiff's reagent (PAS) and Alcian Blue (AB), indicating the presence of neutral and acid mucopolysaccharides. However, the buffle zone was negative for PAS and AB stains, but was positive for all the lectins used. Each zone of the OG had a characteristic pattern of glycan expression. Finally, we confirmed the presence of sperm but not sperm storage. This is the first lectin-histochemical study of the OG in chondrichtyan fish and it has proven to be an important tool to understand some of the mechanisms of fertility and reproductive success in economic important species such as A. platana.

Histological remarks of the uterus of sympterygia acuta (Garman, 1877) and sympterygia bonapartii (Müller & Henle, 1841) (chondrichthyes; rajidae) / Características histológicas del útero de sympterygia acuta (Garman, 1877) y sympterygia bonapartii (Müller & Henle, 1841) (chondrichthyes; rajidae)

Chondrichthyes constitute a conserve and vulnerable clade of increasing importance. However, there is scarce knowledge about the morphological aspects of the reproduction, so that only one work exists about the structure of the gravid uterus of an oviparous species. The work presented here describes the morphological, histological and histochemical remarks of the uterus of two Rajids of the Sympterygia genus along the life cycle. Both species presented paired uteri that lead independently to a common urogenital sinus. The uteri of immature females are filiform, translucent and unspecialized tubes. When sexual development starts, all the genital system displays a transitional and progressive change. In all studied females, independently of the maturing stage, the same four layers were present all over the uterus: a mucosa, which comprises the lining epithelium and lamina propria, a submucosa, a muscular and a serosa. The major changes in the structure of the uterus along the life cycle occur in the mucosa. The uteri of mature, gravid and non-gravid, females presents three distinguishable areas, cranial, medial and caudal, that vary both in the structure and histochemistry of the mucosa and in the thickness of the muscular layer. The results presented here are discussed in a physiological, adaptive and phylogenetic context.

Los condrictios constituyen un clado sumamente conservado y vulnerable a la explotación, que ha cobrado una importancia creciente en los últimos años. Sin embargo, existe poca información sobre los aspectos morfológicos relacionados con la reproducción; tanto así, que la estructura del útero en hembras grávidas sólo ha sido estudiada en profundidad en una especie ovípara. El presente trabajo describe las características morfológicas, histológicas e histoquímicas del útero de dos especies de Rájidos del género Sympterygia a lo largo del ciclo de vida. Ambas especies presentan úteros pares que desembocan independientemente en un seno urogenital común. El útero de las hembras inmaduras es filiforme, translúcido y poco especializado. Cuando se inicia el desarrollo sexual, todo el sistema genital exhibe un cambio direccional y progresivo. En todas las hembras estudiadas, independientemente del grado de madurez, se encontraron las mismas cuatro túnicas a lo largo del útero: una mucosa, compuesta por un epitelio de revestimiento y un corion, una submucosa, una muscular y una serosa. Los cambios mayores en la estructura del útero a lo largo del ciclo de vida ocurren a nivel de la mucosa. En el útero de hembras maduras, grávidas o no grávidas, se pueden reconocer tres regiones claramente diferenciables, craneal, media y caudal, que varían tanto en la estructura como en la afinidad histoquímica de la mucosa, así como en el grosor de la túnica muscular. Los resultados del presente trabajo se discuten en un contexto fisiológico, filogenético y adaptativo.