what are plasma cells and lymphocytes
Often lymphoid aggregates will include a generous number of plasma cells. Remember that plasma cells are the altered B-lymphocytes which produce antibodies. This is an aggregate with lots of plasma cells. Plasma cells have a round, eccentric nucleus with coarse clumps of heterochromatin and euchromatin. It looks more like a soccer ball than a clock face, at least to me.
Lymphocytes are one of the main types of immune cells. Lymphocytes are divided mainly into B and T cells. B lymphocytes produce antibodies - proteins (gamma globulins) that recognize foreign substances (antigen) and attach themselves to them. B lymphocytes (or B cells) are each programmed to make one specific antibody.