Histology and immunohistochemistry of the gut-associated lymphoid tissue of the eastern grey kangaroo, Macropus giganteus

Histomorphological, immunohistochemical, and ultrastructural study on ontogeny of ileocaecal lymphoglandular complexes in prenatal and postnatal Indian buffalo: An innate mucosal immune barrier

The present study was conducted on prenatal and postnatal development of lymphoglandular complexes (LGCs) in ileocaecal region of buffalo fetuses (n = 15) ranging from 11.5 cm curved crown rump length (CVRL) (80 days) to 100 cm CVRL (299 days) and neonatal buffalo calves (n = 10). The fetuses were categorized into three groups based on their CVRL. LGC formation was not evident in ileocaecal junction up to 32 cm CVRL (145 days). At 35 cm CVRL (152 days), diffuse lymphocytes were scattered around the base of glands that encircled them. At 54 cm CVRL (195 days), lymphoid aggregates were present in submucosa around deep submucosal glands and formed primordia of LGCs in ileocaeccal orifice region. At 100 cm CVRL (299 days), these complexes were completely visible grossly. The distinguished lymphoid nodules in submucosa were invaded by submucosal extensions of overlying mucosal glands to form a large clear complex of glands and lymphoid nodules called as "Lymphoglandular complex" at this stage. It is the first report of prenatal development of LGCs in large intestine of buffaloes. Abundant CD3⁺ T cells were observed towards periphery of LGC. In neonates, these complexes were uniform, few with demarcation into dark and light zones that is, germinal center formation. Lymphocytes interspersed in lamina propria were mainly CD3⁺ T lymphocytes. In conclusion, the development of LGCs in ileocaecal region started prenatally in terms of all its cellular components into completely developed and immunocompetent to generate mucosal immunity.

The appearance and distribution of mature T and B cells in the developing immune tissues of the stripe-faced dunnart (Sminthopsis macroura)

This paper describes the initial appearance and distribution of mature T and B cells in the developing immune tissues of the stripe-faced dunnart (Sminthopsis macroura) based on the use of species cross-reactive antibodies to the lymphocyte cell surface markers CD3, CD5 and CD79b. At birth no mature T or B cells were detected in the liver or bone marrow using anti-CD3, anti-CD5 or anti-CD79b antibodies. T cells were detected in the thymus with anti-CD3 by day 12 and anti-CD5 by day 50 postpartum, and T cells in the spleen were detected by day 43 and day 80 postpartum using anti-CD3 and anti-CD5, respectively. B cells were observed in the dunnart spleen by 43 days after birth. CD3- and CD79b-positive cells were detected in the lymph nodes by 50 days and CD5 by day 15 after birth, and in the gut-associated lymphoid tissues by day 50 and anti-CD5 by day 57 postpartum. The development and distribution of T and B cells in the immune tissues of dunnart pouch young is similar to that described in other marsupial species. Low numbers or absence of mature lymphocytes in immune tissues of early pouch young dunnarts further support the proposition that young marsupials are reliant on non-specific defence strategies and/or maternal strategies for a significant period of their time of development in the pouch.

Development of Lymphoid Tissues of the Stripe-Faced Dunnart (Sminthopsis macroura)

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.

Histological and immunohistological investigation of the lymphoid tissue in normal and mycobacteria-affected specimens of the Rufous Hare-wallaby (Lagorchestes hirsutus)

The histology of the spleen, lymph nodes, Gut-associated lymphoid tissue (GALT) and Bronchus-associated lymphoid tissue (BALT) are described for samples collected opportunistically from healthy and mycobacteria-affected specimens of the endangered marsupial Lagorchestes hirsutus, the Rufous Hare-wallaby. The structural elements, organization and distribution of T and B lymphocytes determined by immunohistological techniques using species cross-reactive antibodies in the lymph nodes, spleen and GALT of this species demonstrated lymphoid cell distributions that were consistent with other marsupial and eutherian mammals. The tissues of animals identified as acid-fast positive displayed immunopathology consistent with the responses to intracellular bacteria displayed in some eutherian mammals and included the presence of focal lesions, giant cells in the lung and lymphoid aggregations situated adjacent to blood and airway vessels. This is the first study to describe the lymphoid tissue of this rare macropod species and the first to document the tissue bed response to mycobacteria.

Immunohistochemistry of the lymphoid tissues of the tammar wallaby, Macropus eugenii

The lymphoid tissues of the metatherian mammal, the adult tammar wallaby, Macropus eugenii, were investigated using immunohistochemical techniques. Five cross-reactive antibodies previously shown to recognize surface markers in marsupial tissues and five previously untested antibodies were used. The distribution of T-cells in the tissue beds of spleen, lymph node, thymus, gut-associated lymphoid tissue (GALT) and bronchus-associated lymphoid tissue (BALT) was documented using antibodies to CD3 and CD5. Similarly, B-cells were identified in the same tissues using anti-CD79b. Antibodies to CD8, CD31, CD79a and CD68 failed to recognize cells in these tissue beds. In general the pattern of cellular distribution identified using these antibodies was similar to that observed in other marsupial and eutherian lymphoid tissues. This study provides further information on the commonality of lymphoid tissue structure in the two major groups of extant mammals, metatherians and eutherians.