Microexplants of human thymus: how do the thymic epithelial cells react to lymphocyte death?
The early steps which follow the seeding in culture of human thymic tissue fragments are characterized by a rapid disappearance of lymphatic cells. Under these experimental conditions thymic epithelial cells (TECs) quickly modify their reticular arrangement, assuming an "islet" organization similar to those of epithelial parenchymatous organs. The cytoplasmic projections of TECs surrounding the few surviving thymocytes are lost. Further, the loss of TECs cytoplasmic organelles parallels the reduction of thymocytes, leading to an ultrastructural picture of "undifferentiated" epithelial cells. These findings favour the hypothesis of "one" thymic epithelial cell type, acting as a dynamic unit which adapts its cytological organization to microenvironmental conditions. Further, these observations contribute towards elucidating the reaction of TECs to a selective T-lymphocyte reduction, such as occurs in some human pathological conditions.
Balercia
G
G
Institute of Human Anatomy and Histology, University of Verona, Italy.
Accordini
C
C
Balercia
M
M
D002470:Cell Survival; D002478:Cells, Cultured; D004847:Epithelial Cells; D004848:Epithelium / Q000276:immunology / Q000648:ultrastructure; D006801:Humans; D015388:Organelles / Q000648:ultrastructure; D013601:T-Lymphocytes / Q000166:cytology; D013950:Thymus Gland / Q000166:cytology* / Q000276:immunology