Bobrysheva I.V.
Morphologic and functional features of rats’ thymus in different age periods after experimental immunosuppression
Abstract.
Objectives. To study morphofunctional features of the thymus of white mongrel male rats of different age periods under the conditions of experimental immunosuppression.
180 animals of three age periods (pubertal, reproductive and that of marked age-related changes) served as a material for investigation. Cyclophosphamide was administered to experimental animals once intramuscularly in the dosage leading to immunodepression (200 mg/kg of body weight of an animal). Control animals received 0,9% soluble sodium chloride. Animals were killed by means of decapitation under the ethereal anaesthesia in 1, 7, 15, 30 and 60 days after drug introduction. The сare of and the manipulations on animals were exercised in compliance with the norms of national and international law and the principles of bioethics set out in the Helsinki Declaration. The features of the histological structure of the thymus were studied using an image analyzer based on Olympus CX-41 microscope. The areas of the subcapsular zone, deep cortex and medulla of the thymic lobules, the total number of cells, lymphocytes and epithelial reticular cells on a standard area (104 µm2) of morphofunctional zones, lymphoepithelial index were determined.
The results obtained indicate that rats’ thymus has a high degree of reactivity in response to the administration of cyclophosphamide in high doses. Cyclophosphamide administration to experimental animals results in accidental involution of the thymus, which is expressed in significant changes of morphometric parameters and cytoarchitectonics of the organ within 30 days. Maximum changes of the morphometric parameters are observed in 1 day after cyclophosphamide administration. The animals of the reproductive period and the period of marked age-related changes are characterized by a combination of age (substitution of organ parenchyma by adipose tissue, increase of connective tissue structures) and accidental involution of the organ manifested by delymphotization of the thymic parenchyma morphofunctional zones.
Key words: thymus, rats, cyclophosphamide.
