Development of Lymphoid Tissues of the Stripe-Faced Dunnart <i>(Sminthopsis macroura)</i>

Abstract

The development of the lymphoid tissues of a model marsupial, the stripe-faced dunnart, has been described from birth to weaning, a period of 2.5 months. At birth the lymphoid tissues, including the thymus, lymph nodes and mucosa-associated lymphoid tissues, were undeveloped. A thoracic thymus consisting primarily of stromal tissue was observed by day 4 after birth but by day 12, lymphocytes were observed in the thymus and some cortico-medullary differentiation was apparent. Lymph nodes were histologically mature by day 31, the earliest day investigated for this tissue. In gut tissue, lymphoid follicles were first observed by day 57 post-partum. No bronchus-associated lymphoid tissue was observed in any lung samples. The thymus, lymph nodes and gut-associated lymphoid tissues were all distinguishable before weaning (day 70) but not all were histologically mature. The sequence of development of the lymphoid tissues in the stripe-faced dunnart was similar to those observed in other marsupial species.

A Histological and Immunohistochemical Analysis of Lymphoid Tissues of the Tasmanian Devil

“…The age in which Hassall's corpuscles appears in marsupials varies within different species (Old et al, 2003). Eastern quolls (Dasyurus viverrinus) had Hassall's corpuscles from 7 days after birth (Hill and Hill, 1955) and stripe-faced dunnarts from 40 days of age (Old et al, 2003). Although only one 3-week-old devil was analyzed, it did show structures resembling Hassall's corpuscles, suggesting that the thymus of this devil had at least matured at this age.…”

“…In eutherian mammals, these structures (formed by accumulations of thymic epithelial cells) produce cytokine thymic stromal lymphopoietin, which is involved in maturation of T cells to optimize negative selection and ensure tolerance (Kierszenbaum, 2007). The age in which Hassall's corpuscles appears in marsupials varies within different species (Old et al, 2003). Eastern quolls (Dasyurus viverrinus) had Hassall's corpuscles from 7 days after birth (Hill and Hill, 1955) and stripe-faced dunnarts from 40 days of age (Old et al, 2003).…”

“…However, there remains a lack of basic knowledge about the cellular components and histological architecture of the lymphoid organs of this species. Descriptions of the lymphoid tissues of four small Dasyurids, the brown and dusky antechinus (Antechinus swainsonii and A. stuartii), the stripe-faced dunnart (Sminthopsis macroura), and the red-tailed phascogale (Phascogale calura), have been published (Poskitt et al, 1984a,b,c;Old et al, 2003Old et al, , 2004Old et al, , 2006 and provide important data about this group. Basic information about the immune tissues of the Tasmanian devil, however, is required to better understand the adaptive immune response and its implications for the pathogenesis of DFTD.…”

Dietary composition and nutritional outcomes in two marsupials,Sminthopsis macrouraandS. crassicaudata

“…Gastrointestinal morphology has been described in larger dasyurid species such as spotted-tailed quoll (Dasyurus maculatus), eastern quoll (D. viverrinus), kowari (Dasyuroides byrnei), brush-tailed phascogale (Phascogale tapoatafa), kultarr (Antechinomys laniger), and fat-tailed false antechinus (Pseudantechinus macdonnellensis -Mitchell 1905;Beddard 1908;Stannard and Old 2013). Previously, descriptions of the dunnart gastrointestinal tract have been limited to gross morphology and gut-associated lymphoid tissues (Mitchell 1916;Schultz 1976;Old et al 2003Old et al , 2004. Gross morphology and dimensions were described for the largest species in the Sminthopsis genus, the Julia Creek dunnart (Sminthopsis douglasi- Hume et al 2000).…”

On the prenatal initiation of T cell development in the opossum Monodelphis domestica

“…CD3ε + cells were not evident in Trichosurus vulpecula neonates until postnatal day 2 (Baker et al 1999). In the stripe-faced dunnart, Sminthopsis macroura , CD3ε + cells were observed in 12 days postcoital embryos, and though 1 day postnatal neonates were not tested for CD3 expression their thoracic thymus appeared to be composed mainly of stromal cells at birth (Old et al 2004a,b; Borthwick et al 2014). …”