Ultrastructural morphometry of blastogenesis. II. Stimulated lymphocytes, the progeny of blast cells induced in vivo with DNCB.

As a companion to an earlier study, the morphometric attributes of stimulated (blast-derived) lymphocytes in mouse axillary lymph nodes have been established using stereological and autoradiographic methods. Blast transformation was induced in vivo with dinitrochlorobenzene (DNCB) and stimulated cells were labelled with tritiated thymidine. Random samples of cells were taken for light and electron microscopic morphometry. In comparison to the unstimulated lymphocyte, the stimulated cell increased in size and possessed a greater plasma membrane surface area. Increase in cell size was the result of increases in the volumes of all measured subcellular compartments both in the nucleus and the cytoplasm. Heterogeneity of the stimulated cell population precludes firm conclusions regarding the significance of all these ultrastructural changes, though alterations in cell surface are discussed in the context of known biochemical differences accompanying blastogenesis.