Ultrastructural alterations of the cortical epithelial cells of the irradiated and recovering rat thymus

Abstract

To understand the roles of cortical thymic epithelial cells (CTECs) in T-lymphocyte development, we analyzed rat thymi recovering from irradiation (6Gy), at the ultrastructural level. The morphological alterations in the CTECs were most prominent during the third to fifth day of recovery, when proliferating thymocytes were observed in the vicinity of the CTECs. The most striking finding among the alterations in the CTECs after irradiation was a cytoplasmic vacuolization with an increased amount of granular and membranous content. The granular content was observed as loosely aggregated structures or finely dispersed granules and dense bodies. The membranous content appeared in various forms including vesicular, tubular, and irregular membranous structures and myelin figures. The above features are characteristic of the hyperfunctional state of CTECs with increased secretion activities, which suggests their important roles in the repopulation and maturation of the cortical thymocytes during recovery after irradiation.

Histological study of the role of CD34+ stem cells and mast cells in cyclophosphamide-induced thymic injury in rats and the possible attenuating role of melatonin

“…ERCs also showed significant ultrastructural changes. Similar findings with CP treatment have been observed by other authors (Arudchelvan et al 2005 ; Erokhina and Avilova 2019 ). These changes could be attributed to the cytotoxic effects of CP.…”

“…Some authors reported that the numerous large vacuoles observed in ERCs with CP treatment could be secretory vacuoles, as the ERCs secrete biologically active factors that regulate thymoblast proliferation and maturation, and that the observed increased number of tonofilaments is associated with the exocytosis of these vacuoles. In addition, the vacuoles may be phagocytic vacuoles that engulf the dead thymoblasts and participate in the final breakdown and resorption of the destroyed cells (Arudchelvan et al 2005 ).…”

Single Cell Analysis of Complex Thymus Stromal Cell Populations: Rapid Thymic Epithelia Preparation Characterizes Radiation Injury

“…Having generated data showing that this new TEC isolation method was consistent, we next hypothesized that we could sensitively detect changes in thymocytes and thymic stroma following nonmyeloablative irradiation. Prior studies had suggested that the thymocytes were more susceptible to cell death from radiation than the stroma 37,38 using immunohistochemical techniques. We show that thymocyte number is more significantly affected than TEC after irradiation by enumeration of cell number of both populations in the same cohort of mice.…”

“…With these cytotoxic therapies, the total thymus anlage is decreased, raising the likelihood that immunohistochemical studies may be subject to variations in the size and depth of sections examined. Using this technique, while studies concur that thymocytes are more radiosensitive than TEC, 37–39 assessments of TEC alterations after radiation have differed. Some have suggested that the major effects may occur in the medulla with selective depletion of UEA+ medullary TEC 40,41 and medullary dendritic cells 42 .…”

The Prophylactic Effects of Folic Acid and Vitamin E against Valproic Acid During Fetal Thymus Development: an Ultrastructural Study

“…There is reference to the death of a newborn following therapeutic use of valproic acid in the mother during pregnancy, although no specific information is provided (Depakote Product Label Drugs FDA, 2009). In a study carried out by Arudchelvan et al (2005), it was reported that, in thymic tissue samples,thymocyte had a marked nuclei, and there were vacuoles in cytoplasm. In our study, in addition to the points mentioned above, we observed that desmosomal structures were normal.…”