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Morphology of complex lymphoepithelial organs of the anal canal (“anal tonsil”) in the bottlenose dolphin, Tursiops truncatus
Author(s) -
Cowan Daniel F.,
Smith Toby L.
Publication year - 1995
Publication title -
journal of morphology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.652
H-Index - 74
eISSN - 1097-4687
pISSN - 0362-2525
DOI - 10.1002/jmor.1052230304
Subject(s) - biology , tonsil , anatomy , bottlenose dolphin , lymphatic system , epithelium , anal canal , pathology , stratified squamous epithelium , mucus , rectum , immunology , ecology , medicine , genetics
A complex of lymphoepithelial organs, the “anal tonsils,” is a consistent structure in the anal canal of the bottlenose dolphin, Tursiops truncatus. This complex occurs as a circumferential cluster of discrete tonsil like aggregations of lymphoid tissues, together with epithelial ducts (“crypts”) and occasional mucus secretory units in the extreme lower portion of the intestinal tract. These structures are concentrated in the segment lined by stratified squamous epithelium and extend for a variable distance cephalad from the anal aperture. The tonsils appear to be most active, judged by the amount of lymphoid tissue present, in young animals. Depletion of lymphocytes and cystic enlargement of the crypts, probably representing functional as well as morphological involution, is a consistent feature of older animals. © 1995 Wiley‐Liss, Inc.