Journal Molluscan Studies Advance Access originally published online on June 28, 2005
Journal of Molluscan Studies 2005 71(3):269-300; doi:10.1093/mollus/eyi036
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AN ULTRASTRUCTURAL STUDY OF THE GLAND OF LEIBLEIN OF MURICID AND NASSARIID NEOGASTROPODS IN RELATION TO FUNCTION, WITH A DISCUSSION ON ITS HOMOLOGIES IN OTHER CAENOGASTROPODS
School of Biological Sciences & EM Unit, Royal Holloway, University of London, Egham, Surrey, TW20 0EX, UK
Correspondence: E. B. Andrews; e-mail: e.b.andrews{at}rhul.ac.uk
The gland of Leiblein of the muricid Nucella lapillus and the nassariid Hinia reticulata has been examined by scanning and transmission electron microscopy. The origin and functional significance of its complex organization and its relationship with the rest of the mid-oesophagus in Nucella are discussed. It is absorptive as well as secretory, and a mechanism is proposed by which solute-rich fluids may enter the gland. Its epithelium is composed of occasional mucous cells and two major cell types: ciliated cells engaged in protein metabolism and unciliated cells responsible for uptake and storage of lipids and carbohydrates, both of which show evidence of pinocytotic uptake of solutes and intracellular digestion in lysosomes. Some enzyme activity persists in the residual bodies they shed by apocrine secretion, but they remain intact in a mucous string until they reach the stomach. Preliminary ultrastructural examination indicates that the gland absorbs cadmium not only from the blood but also directly from its lumen and that it may have the capacity to sequester a wide range of toxins. The same types of cell occur in Hinia in which their cyclical activity has been correlated with feeding. Similar cells have been identified in the oesophageal glands of other prosobranchs. The foregut glands of carnivorous caenogastropods are compared with the gland of Leiblein. There is an inverse correlation between the role of the mid-oesophagus in digestion and absorption and the complexity of the stomach.
(Received 16 August 2004; accepted 24 January 2005)