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A study of the tonsillar developments in the lingual region of anurans
Author(s) -
Myers Mabel A.
Publication year - 1928
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.1050450202
Subject(s) - biology , toad , bufo , mesenchyme , metamorphosis , anatomy , thyroid , connective tissue , tonsil , epithelium , zoology , larva , ecology , endocrinology , immunology , genetics
In this study the problem of the tonsil is considered in anurans. The common toad (family Bufonidae) is used as the type, and representative species of the other families are compared. In each species representative stages beginning before transformation were selected, and the lingual region of each was sectioned. Some thyroid‐fed toad tadpoles which had prematurely transformed were examined. The investigations led to the following conclusions: 1 Accumulations of lymphocytes occur in all the families except Hylidae. 2 A pair of tonsils located on either side of the tongue appear before transformation in Bufo, and persist, increasing in size through old age. 3 This pair has its developmental origin at or near the cephalic end of pouch II. In no other species examined do the tonsils appear as early; in almost all forms the accumulations are inconstant in occurrence, as are also some in Bufo. 4 The cells of the ‘tonsils’ are lymphocytes of varying sizes. They arise from the mesenchyme; later their accumulations become sites of lymphopoiesis. 5 This type of lympho‐epithelial mass is simple in structure and has a greatly thickened epithelium, due to extensive infiltration by lymphocytes. In the connective tissue the vascular supply is abundant. 6 The differentiation of lymphocytes may be due to a factor of strain, arising through adjustments made during metamorphosis. 7 Thyroid‐fed toad tadpoles transform, apparently without developing tonsils.