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Lobo-Da-Cunha A.,University of Porto | Lobo-Da-Cunha A.,CIIMAR - Interdisciplinary Center of Marine and Environmental | Lobo-Da-Cunha A.,Portuguese Institute of Malacology IPM | Santos T.,CIIMAR - Interdisciplinary Center of Marine and Environmental | And 5 more authors.
Journal of Molluscan Studies | Year: 2011

A histochemical and ultrastructural study of the crop and oesophagus was carried out for the first time in Aglajidae. In Philinopsis depicta, the hind region of the crop contains two large folds creating a channel between them, lined by a ciliated epithelium. This ciliated groove continues through the posterior oesophagus. In addition to these larger folds, both crop and posterior oesophagus present many smaller longitudinal ridges lined by a nonciliated epithelium formed by cells bearing microvilli embedded in a layer of extracellular material. Lysosomes and mitochondria are common in the supranuclear region of these cells, and in the basal region hemidesmosomes are frequent. Epithelial secretory cells contain many large vesicles with a low electron-density content rich in acid polysaccharides, but without detectable amounts of protein. The basal region of the secretory cells comprises the nucleus and several Golgi stacks formed by many flat cisternae with low electron-density content. Secretory cells were not observed in the ciliated epithelium of the channel between the two large folds. The connective tissue of the crop and posterior oesophagus contains many large vacuolar cells with a thin layer of cytoplasm around the single vacuole that occupies about 90 or more of the cell volume. Tubular invaginations of the cell membrane are frequent in these cells and some also contain large vesicles that can open to the central vacuole, suggesting an intense transport activity across the cytoplasm. These vacuolar cells could be related to the calcium cells reported in the connective tissue of other gastropods. Ultrastructural and histochemical studies of the organs of the digestive system in carnivorous and herbivorous cephalaspideans can lead to the discovery of important unknown features, like the vacuolar cells, which might be useful to establish correlations with molecular phylogenetic data or food sources. © The Author 2011. Published by Oxford University Press on behalf of The Malacological Society of London, all rights reserved. Source

Lobo-da-Cunha A.,University of Porto | Lobo-da-Cunha A.,CIIMAR - Interdisciplinary Center of Marine and Environmental | Lobo-da-Cunha A.,Portuguese Institute of Malacology IPM | Alves A.,University of Porto | And 5 more authors.
Thalassas | Year: 2011

In order to obtain more data for a comparative analysis of the digestive system in opisthobranchs, the stomach and intestine of Bulla striata were studied with light and electron microscopy. A 3D-model of the stomach and its connections with the posterior oesophagus, digestive gland ducts and intestine was created from a series of histological sections. The U-shaped stomach is just a segment of the digestive tube without any external distinction from the intestine. Internally, the stomach is characterized by the presence of a typhlosole and many mucussecreting cells that are strongly stained by PAS reaction and alcian blue. Significant amounts of proteins were not detected in the mucus-secreting cells of the stomach, but protein-rich secretory material was found in the apical region of another type of secretory cells present in both stomach and intestine. The end of the typhlosole can be considered the transition point between the stomach and intestine. Mucus-secreting cells are also abundant in the intestine and all of them stain with alcian blue. However, most mucus-secreting cells of the intestine are not significantly stained by PAS reaction, but contain more proteins than the mucus-secreting cells of the stomach. The granular cells with a large number of small electron-dense secretory vesicles containing proteins and neutral polysaccharides were found only in the intestine. The available data show that despite some anatomical and histological differences several cell types are identical in the digestive systems of Aplysia depilans and B. striata. Source

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