Activation of cortical and inhibited differentiation of medullary epithelial cells in the thymus of lymphotoxin-beta receptor-deficient mice: an ultrastructural study.
The reciprocal influences of thymic lymphocyte and nonlymphocyte populations, i.e. thymic cross-talk, are necessary for the proper maturation of thymocytes and the development/maintenance of thymic stromal microenvironments. Although the molecular influences exerted by thymic stromal cells on maturing thymocytes have been extensively studied, the identity of signalling molecules used by thymocytes to influence the thymic stromal cells is still largely unknown. Our study provides the first ultrastructural evidence that the functional lymphotoxin-beta receptor (LTbetaR) signalling pathway is engaged in the cross-talk between thymocytes and the thymic stromal cell population. We show that LTbetaR signalling is of the utmost significance for the preservation of the subcellular integrity of all thymic epithelial cells. In the absence of LTbetaR there is (1) hypertrophy and activation of cortical thymic epithelial cells, (2) the complete loss of fully differentiated medullary thymic epithelial cells, and (3) the inhibited differentiation of remaining medullary thymic epithelial cells with the appearance of prominent intercellular cysts in the thymic medulla.
Milićević
N M
NM
Institute of Histology and Embryology, Faculty of Medicine, University of Beograd, Serbia. emilicen@etf.bg.ac.yu
Nohroudi
K
K
Milićević
Zì
Z
Westermann
J
J
D000818:Animals; D004847:Epithelial Cells / Q000000981:diagnostic imaging*; D005260:Female; D053259:Lymphotoxin beta Receptor / Q000172:deficiency*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008854:Microscopy, Electron / Q000379:methods*; D013950:Thymus Gland / Q000648:ultrastructure*; D014463:Ultrasonography
D053259:Lymphotoxin beta Receptor