An Examination of the Development and Localization of Key Immune Cells in Developing Pouch Young of the Red-Tailed Phascogale (Phascogale calura).

Cells expressing the surface markers CD3, CD4, CD79b, IgM, MHC class II, and ModoUG (nonclassical MHC class I) were detected in red-tailed phascogale tissues using immunohistochemistry, and the appearance and localization of cells observed here was consistent with previous observations in other marsupial species. CD3+ cells were first detected at one day postpartum (dpp) in the thymus, followed by ModoUG+ cells at 5-7 dpp in the thymus and lymph nodes. CD79b+ cells were first detected at 12-14 dpp in bone marrow, spleen, and lymph nodes. IgM+ cells were first detected at 12-14 dpp in thymus, bone marrow, spleen, and lymph nodes. MHC class II+ cells were first detected at 12-14 dpp in thymus, bone marrow, and lymph nodes. CD4+ cells were detected in adult thymus and spleen only. The presence of the mature immune cell populations and their localization to characteristic T and B cell zones in mature lymphoid tissues with normal histological structure indicates that red-tailed phascogales develop immunocompetence by the end of pouch life. Anat Rec, 302:1985-2002, 2019. © 2019 American Association for Anatomy.