Abstract
The present work reports on an electron microscopic study of the primary response of two strains of rats to the subcutaneous injection of the hapten 2,4-dinitrophenyl (DNP). When this substance is injected into the two strains used, there is either a weak or a strong production of circulating anti-DNP antibodies. Satellite lymph nodes were fixed in glutaraldehyde, incubated in a solution of horseradish peroxidase labeled with DNP and treated with diaminobenzidine + H2O2. A specific positive reaction was observed: (a) in the perinuclear cisternae of numerous lymphocytes and lymphoblasts; (b) in the perinuclear cisternae as well as in the peripheral cisternae of some plasmablasts; and (c) in a recently described rare type of cell known as a "lymphoplasmacyte." In certain lymphocytes, there was an accumulation of the reaction product in the perinuclear cisternae, and sometimes in the peripheral cisternae, which, in some places, provoked a dilation of the cisternae. There was no significant qualitative difference between the two strains of rats.