Cortical areas devoid of follicles were also devoid of T cell zones. As a consequence, overall numbers of T cells in the pancreas of Aselli often seemed lower in adult than sub-adult animals. Where the cortex was devoid of follicles, plasma cells extended from the medulla to the marginal sinuses or beyond to the capsule, such that the medulla often occupied most of the organ in adult animals (Fig. 3B) . Accordingly, in adult animals, the whole organ frequently appeared as an accumulation of plasma cells, surrounded by a fragmentary cortex and paracortex.