Oesophageal pouch explained

The oesophageal pouches (also known as sugar glands) are a pair of pouches connected to the oesophagus of all molluscs, and represent a synapomorphy of the phylum.[1]

Morphology

Usually forming a pair of lateral structures, oesophageal pouches take various forms, but usually account for a fair portion of the anterior volume of the creeping molluscs and scaphopods.[2] [3] [4] [5] [6] There is a single pouch ventral to the rear of the radula in some nudibranch sea slugs.The pouches are lined with ciliated secretory cells.[7]

Function

The pouches contain digestive enzymes that break down starch and other polysaccharides,[8] and also extrude mucus.

Occurrence

The features are considered ancestral to molluscs[1] and are present in monoplacophorans,[9] but have been secondarily lost in the Heterobranchia.[10] However, it is not certain that all oesophageal diverticulae are homologous.[11] [12]

Notes and References

  1. Book: The mollusks: a guide to their study, collection, and preservation. 978-1-58112-930-4. Sturm. Charles F. Pearce. Timothy A. Valdés. Ángel. July 2006.
  2. 10.1111/j.1463-6409.1987.tb00077.x . Haszprunar . G. . Anatomy and affinities of cocculinid limpets (Mollusca, Archaeogastropoda) . Zoologica Scripta . 16 . 4 . 305–324 . 1987 . 222189563 .
  3. 10.1111/j.1463-6395.1989.tb01068.x . Haszprunar . G. . The Anatomy of Melanodrymia aurantiaca Hickman, a Coiled Archaeogastropod from the East Pacific Hydrothermal Vents (Mollusca, Gastropoda) . Acta Zoologica . 70 . 3 . 175–186 . 1989 .
  4. 10.1093/mollus/eyq013. Ruthensteiner . B. . Schropel . V. . Haszprunar . G. . Anatomy and affinities of Micropilina minuta Warén, 1989 (Monoplacophora: Micropilinidae) . Journal of Molluscan Studies . 76 . 4 . 323–332 . 2010 . free .
  5. Crampton . D. M. . Functional anatomy of the buccal apparatus of Onchidoris bilamellata (Mollusca: Opisthobranchia) . The Transactions of the Zoological Society of London . 34 . 45–86 . 2010 . 10.1111/j.1096-3642.1977.tb00372.x .
  6. 10.1093/mollus/eyi008 . Urgorri . V. . García-Álvarez . O. . Luque . Á. . Laevipilina Cachuchensis, A New Neopilinid (Mollusca: Tryblidia) from off North Spain . Journal of Molluscan Studies . 71 . 59–66 . 2005 . free .
  7. 10.1017/S0025315400006032 . Morton . J. E. . The habits and feeding organs of Dentalium entalis . Journal of the Marine Biological Association of the United Kingdom . 38 . 2 . 225–238 . 2009 . 86547255 .
  8. 10.1093/oxfordjournals.mollus.a064810. The Distribution of Cellulases and Related Enzymes in Mollusca. Journal of Molluscan Studies. 1958.
  9. 10.1093/mollus/eyq013. Ruthensteiner . B. . Schropel . V. . Haszprunar . G. . Anatomy and affinities of Micropilina minuta Warén, 1989 (Monoplacophora: Micropilinidae) . Journal of Molluscan Studies . 76 . 4 . 323–332 . 2010 . free .
  10. 21–32 . 1991 . 10.1093/mollus/57.1.21 . 57 . Journal of Molluscan Studies . Marine Valvatoidean Gastropods—Implications for Early Heterobranch Phylogeny. Ponder . W. F. .
  11. 10.1111/j.1463-6395.2009.00392.x . Lobo-Da-Cunha . A. . Oliveira . E. . Alves . Â. . Coelho . R. . Calado . G. . Light and electron microscopic study of the anterior oesophagus of Bulla striata (Mollusca, Opisthobranchia) . Acta Zoologica . 91 . 2 . 125–138 . 2010 . free .
  12. Mikkelsen PM. The evolutionary relationships of Cephalaspidea S.L. (Gastropoda: Opisthobranchia): A phylogenetic analysis . 1996 . Malacologia. 37. 375–442.

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