The Thymus in the Marsupials.

Johnstone, James

doi:10.1111/j.1096-3642.1898.tb00410.x

Cited by 15 publications

(8 citation statements)

References 2 publications

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“…There have been four reported investigations on the status of the thoracic thymus in koalas and wombats (Johnstone, 1898;Symington, 1900;Fraser, 1915;Yadav, 1973). A thoracic thymus has been identi®ed in two of the total 15 dissections of koalas described by these four authors.…”

Section: Discussionmentioning

confidence: 99%

The marsupial and monotreme thymus, revisited

Haynes

2001

Journal of Zoology

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The anatomy and histology of the thymus in monotremes and marsupials were revisited and several new observations made. Tissues of the mediastinum and / or ventral neck of 134 animals altogether (12 Australian marsupial and monotreme species) were examined and the locations of thymic tissues documented. Descriptions not previously recorded include the gross anatomy of the thymus in monotremes, the bandicoot (Isoodon macrourus, Isoodon obesulus), the wombat (Lasiorhinus latifrons), and koala (Phascolarctos cinereus), as well as light and electron microscopic features in all species examined. In monotremes, thymic tissue was diffusely spread in the mediastinum and extended over the ventral surface of the pericardium. In the bandicoot, a small, deep cervical thymus was persistently present as well as the expected thoracic thymus and contrary to previous observations, a thoracic thymus was found in the wombat but not the koala. Both species also have a cervical thymus. In the marsupial species examined, additional thymic tissue was often present in the vicinity of the carotid bifurcations, in the deep ventral regions of the neck. In many animals, thymic tissue of deep cervical origin as well as thoracic thymus was mingled with parathyroid tissue. In several specimens, the two tissue types lacked intervening connective tissue barriers and at the electron microscopic level, attenuated processes of epithelial reticular cells were the only tissue components separating parathyroid and thymic tissues. The role of the cervical thymus in diprotodont marsupials remains to be elucidated. The presence of aberrant thymic tissue in marsupials is important in the interpretation of experiments involving thymectomy and immunological development because complete removal of thymic tissue may not occur. One aspect that has received little attention is the function of the thymic epithelial reticular cells in marsupial development and a suggestion is made that perhaps the extra thymic tissue found in marsupials provides extra epithelial reticular cells necessary for the production of cytokines and other secretions to sustain the development of immunological competence.

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Section: Discussionmentioning

confidence: 99%

The marsupial and monotreme thymus, revisited

Haynes

2001

Journal of Zoology

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“…The exception to this is the koala ( Phascolarctos cinereus ), in which a lone thoracic thymus is more commonly found [20]. Early studies focused on topological and anatomical descriptions of the thymuses including details on their organogenesis and relative growth rate [12-15,18,19,22]. Later, histological studies were used to determine the time of T-cell maturation [23-27].…”

Section: Introductionmentioning

confidence: 99%

Transcriptomic analysis supports similar functional roles for the two thymuses of the tammar wallaby

et al. 2011

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BackgroundThe thymus plays a critical role in the development and maturation of T-cells. Humans have a single thoracic thymus and presence of a second thymus is considered an anomaly. However, many vertebrates have multiple thymuses. The tammar wallaby has two thymuses: a thoracic thymus (typically found in all mammals) and a dominant cervical thymus. Researchers have known about the presence of the two wallaby thymuses since the 1800s, but no genome-wide research has been carried out into possible functional differences between the two thymic tissues. Here, we used pyrosequencing to compare the transcriptomes of a cervical and thoracic thymus from a single 178 day old tammar wallaby.ResultsWe show that both the tammar thoracic and the cervical thymuses displayed gene expression profiles consistent with roles in T-cell development. Both thymuses expressed genes that mediate distinct phases of T-cells differentiation, including the initial commitment of blood stem cells to the T-lineage, the generation of T-cell receptor diversity and development of thymic epithelial cells. Crucial immune genes, such as chemokines were also present. Comparable patterns of expression of non-coding RNAs were seen. 67 genes differentially expressed between the two thymuses were detected, and the possible significance of these results are discussed.ConclusionThis is the first study comparing the transcriptomes of two thymuses from a single individual. Our finding supports that both thymuses are functionally equivalent and drive T-cell development. These results are an important first step in the understanding of the genetic processes that govern marsupial immunity, and also allow us to begin to trace the evolution of the mammalian immune system.

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“…The Tasmanian devil has been recently afflicted with a fatal facial tumour, which makes an understanding of their immune system an important management issue. To date, studies of members of the Dasyuromorphia have been limited to documenting anatomical position and cellular structure, including involution of the thymus (Johnstone, 1898;Symington, 1898;Hill & Hill, 1955;Yadav, 1973;Poskitt et al 1984a;Haynes, 1991). Most recently we have documented the development of the lymphoid tissues in the small dasyurid Sminthopsis macroura (Old et al 2003a(Old et al , 2004.…”

Section: Introductionmentioning

confidence: 99%

The immune tissues of the endangered red‐tailed phascogale (Phascogale calura)

et al. 2006

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The lymphoid tissues of the red-tailed phascogale (Phascogale calura) were examined using histological and immunohistochemical techniques. The distribution of immune cells in the tissue beds was documented using antibodies to surface markers CD3 and an MHC Class II antigen (equivalent to HLA DRII). Spleen, gut-associated lymphoid tissues (GALT), lung, bronchus-associated lymphoid tissue (BALT) and liver were examined. The spleen had defined areas of red and white pulp, with follicles containing tingible-bodied macrophages. Anti-CD3 and anti-HLA DRII antibodies revealed the presence of T cells in areas of white pulp and around the peri-arterial lymphatic sheaths.GALT and BALT were detected and appeared as scattered areas of lymphocytes in the tissues beds. This is the first study to report on the lymphoid tissues of this endangered species of marsupial and the first report of the capacity of anti-human antibodies to a surface MHC molecule to react with Dasyurid cells.

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The Thymus in the Marsupials.

Cited by 15 publications

References 2 publications

The marsupial and monotreme thymus, revisited

The marsupial and monotreme thymus, revisited

Transcriptomic analysis supports similar functional roles for the two thymuses of the tammar wallaby

The immune tissues of the endangered red‐tailed phascogale (Phascogale calura)

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