Cells Containing Birbeck Granules (Langerhans Cell Granules) in the Human Thymus

Abstract

In the thymuses of a 6-year-old female and a 7-year-old male cells containing Birbeck granules (Langerhans cell granules) were found by electron microscopy. The cells occurred not only within the mesh of the epithelial reticulum but also in the interstitial connective tissue. They were characterized by the presence of the Birbeck granules in relatively clear cytoplasm and by a nucleus of irregular outline. The mesenchymal nature of the cells was suggested by the lack of tonofilaments or a basement membrane surrounding them. Signs of phagocytic activity were absent from these cells. Therefore they were considered as a cell type morphologically distinct from other types of cells in the human thymus. The relationship of the cells to the Birbeck granule-containing cells in other tissues was discussed.