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Histochemical and Ultrastructural Characterization of the Posterior Esophagus of Bulla striata (Mollusca, Opisthobranchia)

Published online by Cambridge University Press:  01 October 2010

Alexandre Lobo-da-Cunha*
Laboratory of Cell Biology, Institute of Biomedical Sciences Abel Salazar (ICBAS), University of Porto, 4099-003 Porto, Portugal Centre of Marine and Environmental Research (CIIMAR), 4050-123 Porto, Portugal Portuguese Institute of Malacology, 8201-864 Guia, Portugal
Elsa Oliveira
Laboratory of Cell Biology, Institute of Biomedical Sciences Abel Salazar (ICBAS), University of Porto, 4099-003 Porto, Portugal
Íris Ferreira
Laboratory of Cell Biology, Institute of Biomedical Sciences Abel Salazar (ICBAS), University of Porto, 4099-003 Porto, Portugal
Rita Coelho
Portuguese Institute of Malacology, 8201-864 Guia, Portugal
Gonçalo Calado
Portuguese Institute of Malacology, 8201-864 Guia, Portugal Lusophone Universityof Humanities and Technologies, 1749-024 Lisbon, Portugal Institute for Marine Research (IMAR), FCT/UNL, 2829-516 Caparica, Portugal
Corresponding author. E-mail:
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The posterior esophagus of Bulla striata, running from the gizzard to the stomach, was investigated with light and electron microscopy to obtain new data for a comparative analysis of the digestive system in cephalaspidean opisthobranchs. In this species, the posterior esophagus can be divided into two regions. In the first, the epithelium is formed by columnar cells with apical microvilli embedded in a cuticle. Many epithelial and subepithelial secretory cells are present in this region. In both, electron-lucent secretory vesicles containing filaments and a peripheral round mass of secretory material fill the cytoplasm. These acid mucus-secreting cells may also contain a few dense secretory vesicles. In the second part of the posterior esophagus, the cuticle is absent and the epithelium is ciliated. In this region, epithelial cells may contain larger lipid droplets and glycogen reserves. Subepithelial secretory cells are not present, and in epithelial secretory cells the number of dense vesicles increases, but most secretory cells still contain some electron-lucent vesicles. These cells secrete a mixture of proteins and acid polysaccharides and should be considered seromucous. The secretory cells of the posterior esophagus are significantly different from those previously reported in the anterior esophagus of this herbivorous species.

Special Section from Portugal Meeting
Copyright © Microscopy Society of America 2010

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