Small amount of radioactive material released in the environment from coal and nuclear power plants and also from nuclear explosions are also source of radiation exposure to man. Exposure to high doses of radiation can cause nausea and vomiting within few hours whereas low levels of radiation exposure doesn’t cause immediate health effects but can increase cancer risks. Ionizing radiation can cause tissue damage by changing the chemical properties of molecules. It produces free radicals which are chemically very active and damage the genetic material of a living cell. The present study was therefore designed to investigate the histopathological changes in spleen of Swiss albino mice after radiation exposure. For the experiment, adult healthy male Swiss albino mice were irradiated at the dose rate ranging from 0.97 Gy/min. to 1.97 Gy/min. The dose was calculated at mid-point by multiplying dose rate and tissue air ratio. Animals were exposed to sublethal dose of gamma radiation from Co60 source. Five animals from each group were autopsied by cervical dislocation at each post-interval of 1, 2, 4, 7, 10, 14, and 28 days. Before autopsy the weight of the animals was also recorded. Five normal mice were also autopsied. After autopsy spleen was taken out, weighed on mono pan electric balance. After recording weight, tissue was fixed in Bouin’s fluid for 24 hours for histological studies. Spleen is a radiosensitive tissue and shows reduction in body weight and organ weight ratio reaching minimum till day 10 after radiation exposure. Loss of splenic weight was mainly due to cellular damage, loss of lymphocytes, mitosis and circulatory and humoral disturbances. Most striking histopathological change in the spleen in the present study was the rapid death of lymphocytes. Decrease in the total cell population in the present study may be due to direct killing of small lymphocytes by radiation and due to death of cells in their attempt to divide. During later intervals, the new germinal centers were gradually repopulated and lymphocyte cap begins to surround them. At the end of the experiment, although spleen represented all the normal cell types however, recovery was not complete as far as cell population and cell arrangement was considered.
Keywords: Radiation, Spleen, Lymphocytes.
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