1. Blast transformation of lymphocytes by phytohemagglutinin (a non-specific mitogenic lectin) shows the same type of intra-cellular changes and subsequent development into lymphoblasts as those that occur in vivo to primed lymphocytes when they are re-introduced to the priming antigen.

2. T-cell blasts are large cells with extended cytoplasm. Ultimately, many B-cell blasts mature into terminally differentiated plasma cells.

3. Under the light microscope, following mitogenic stimulation, you see an increase in the number of these larger blast cells. Compare the two photographs to see these results.
   • Notice that virtually all of the cells in the left photo are small cells with compact nuclei - none have undergone blastogenesis.

   • Notice the increased number of large cells in the right photo - cells that have been stimulated into undergoing blastogenesis.

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