Lymph node histology in transgenic pigs.

<p>Developmental stage of lymph nodes of a 6-month-old CAG-LEA transgenic pig (B, E) in comparison with WT porcine lymph nodes; the age of the animals was 19 days (A, D) and 6 months (C, F). Immunohistochemistry using the PPT3 anti-CD3 antibody demonstrates nearly T cell-free follicles (Fo) near the trabecules (T) in all samples. Follicles in samples of 6-month-old WT animals were generally larger than in transgenic or young animals (compare C versus A and B). Follicles of 6-month-old WT porcine lymph nodes showed a distinct reaction center (F) with heavily proliferating centroblasts in the dark zone (DZ) and less proliferating cells in the pale zone (PZ)–comparing strong and weak Ki67 immunopositivity (proliferation marker) in DZ and PZ, respectively. In contrast, marked proliferation of lymphocytes could be detected in either the follicles of transgenic (E) nor 19-day-old WT animals (D). The amount of proliferating T cells did not seem to differ between the samples. Visualization of the immunoreaction diaminobenzidine—horseradish peroxidase (positive staining = brown), counterstaining hematoxylin, scale bar = 200 μm.