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.