An examination of the development and localisation 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 (non‐classical MHC class I) were detected in red‐tailed phascogale tissues using immunohistochemistry, and the appearance and localisation of cells observed here was consistent with previous observations in other marsupial species. CD3+ cells were first detected at 1 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 detected and their localisation 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.