Ultrastructure of Cells Present in Lymph Nodes During the Development of Contact Sensitivity

Abstract

Lymph nodes from guinea-pigs have been examined by electron microscopy between 3 and 6 days after the application of the chemical sensitizing agent 2-phenyl-4-ethoxy-methylene-oxazolone. A striking feature of the lymph node reaction was the appearance of many large cells (immunoblasts) characterized by the presence of many polyribosomal clusters in the cytoplasm. The ultrastructural differences between these cells and other cells belonging to the lymphocytic series (i. e. small lymphocytes, intermediate cells) are described and discussed. The intermediate cells are a stage in the transformation of immunoblasts into small lymphocytes following cell division.