| Popis: |
The effect of estrogen (E), a female sex steroid, on the thymus tissues from castrated female mice treated with E was examined by molecular biologic, microscopic and flowcytometric techniques. First, using an oligoprobe for E receptor (ER)-messenger RNA (ER-mRNA), one hybridized band was found at 6.2 kilobase (kb) in mouse thymus tissue, as was also the case in the human breast cancer MCF-7 cell line. ER-mRNA level in the E-treated animals was almost 3 times that in oil-treated controls. Secondly, an electron microscopic observation indicated E treatment to bring about apoptosis of thymocytes (T cell) which were embraced by thymic stromal cells (possibly phagocytic in nature) and/or ballooning of the endoplasmic reticulum in the epithelial cells with abundant lipid droplets. Thirdly, flow cytometric analysis demonstrated E to induce the change of T cell subpopulations: an increase in helper/inducer (L 3 T 4 + Lyt 2 − ) cells with decrease in the double positive (L 3 T 4 + Lyt 2 + ) cells. It follows from the above findings that E may cause morphologic changes in the thymus closely related to T cell differentiation. In addition, these changes appear to derive mainly from E-induced tissue-specific gene expression including that of ER-mRNA. |
Full Text from ScienceDirect