Revised seminology of the different mononuclear cells under scanning electron microscopy.

Scanning electron microscopy shows that the thymus cell surface is not smooth but slightly undulated; this type of surface characteristic is found on the cells of several types of T-lymphocyte tumors such as T-cell lymphosarcoma, mycosis fungoides, and T-immunoblastic lymphosarcoma. The cell surface of Frabricius' bursa is covered with numerous short villi. They are found on the cells of several kinds of B-lymphocyte tumors, including B-cell chronic lymphoid leukemia, B-prolymphocytic lymphosarcoma, and B-immunoblastic lymphosarcoma. Mycosis fungoides cells frequently have a characteristic shape. Normal and myeloma plasma cells are similar in shape but their surface is covered with numberous characteristic tiny balls. Immunoblasts are twice the size of so-called small lymphocytes. In the blood and in the lymphocyte population transformed by mitogens, cell surfaces vary from completely smooth (with no undulations as in thymic cells) to villous, with short to very long villi. These variations are visible even when a constant technique and the critical-point drying method are used. Their significance, however, is not known.