Morphological changes in the thymus of rats of reproductive period on the background of the immunosuppressant cyclophosphamide administration

Aim. To study the features of morphological changes of the thymus gland (thymus) of reproductive period rats amid the administration of the immunosuppressant cyclophosphamide.

Methods. Thymus preparations were studied using an image analyzer based on CX-41 Olympus microscope. The morphological and functional areas of the thymus were determined relative areas (as a percentage) occupied by subcapsular, inner cortical zones of the cortex and thymic lobules medulla; cells distribution density, the percentage of cellular elements: lymphoblasts, small, medium and large lymphocytes, macrophages, mitotically dividing, destructively altered cells epithelioreticulocytes.

Results. A statistically significant reduction in the relative area of subcapsular and inner cortical zones of the cortex, as well as an increase in this parameter in the thymic medullary parenchyma after 1-30 days after administration of cyclophosphamide were found. The cell density is reduced both in the cortex and in the medulla. Cytoarchitectonics of the thymus morphological and functional zones changes: a decrease in relative content of lymphocytes, mainly of young forms, as well as increase in the percentage of macrophages and destructively altered cells occurred. Maximum deviations of studied parameters was recorded after 1 and 7 days after drug administration. In 60 days after cytostatic administration morphometric characteristics of the thymus morphological and functional zones in laboratory rats do not have significant differences from the parameters in control animals of appropriate age.

Conclusion. A single administration of cyclophosphamide leads to acute thymic involution, which is manifested in a decrease in the relative area of the cortex, lobules deformation, organ fatty degeneration, decrease in the relative content of lymphocytes, increase in the percentage of macrophages and destructively modified cells, which may be indicative of a high degree of reactivity of the animals thymus; results of the study may serve as morphologic evidence of the damaging effect of cyclophosphamide on the thymus lymphoid tissue.