This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Boniver, J. Articles by Betz, E. H. Search for Related Content PubMed PubMed Citation Articles by Boniver, J. Articles by Betz, E. H.

Quantitative Analysis of Thymus Lymphoid Cells during Murine Radioleukemogenesis¹

Laboratory of Morbid Anatomy, Institute of Pathology, State University of Liège, Sart Tilman, 4000 Liège, Belgium

Fractionated irradiation by four doses of 150 R leads to the development of lymphoma in the thymus of C57BL mice, after a long latent period (4 to 12 months) during which thymic subcapsular blast cells undergo neoplastic transformation. Electron microscope studies on this blast cell population have revealed several types that are distinguishable on the basis of nuclear ultrastructure and activity in the cell cycle. These blast cells are lymphoblasts, ring-shaped nucleolus cells, and X-cells.

A stereological analysis demonstrates that the result of the irradiations is not an increase of the thymic blast cell number during the preleukemic period, as generally thought before, but important modifications in the relative proportion of the three cell types forming the blastic population. X-cells, which essentially appear in S phase, are more numerous after the third and fourth doses of radiation. They might be more "sensitive" to the action of the leukemogenic virus and facilitate the leukemogenic process. In contrast, in the preleukemic atrophic thymus just before the appearance of the lymphoma, X-cells are scarce, and ring-shaped nucleolus cells are more frequent than in the controls, suggesting important changes in thymus cell kinetics.

The only modification detected in the blast cells at any time after irradiation concerns the surface of Golgi membranes, which decreases in X-cells and ring-shaped nucleolus cells of the atrophic thymus. Because the same change is observed later on in the lymphomatous cells, it is suggested that the change might be related to the transformation of the thymic blast cells into cancerous cells.

¹ Supported by the Fonds de la Recherche Scientifique Médicale and the Centre Anticancéreux près l'Université de Liège, Belgium.

Received 5/ 3/77. Accepted 9/27/77.