Effect of gonadectomy and oestrogen administration on the response of lymph-node post-capillary venules to infection with Toxoplasma gondii.

The effects of gonadectomy and oestrogen administration on the response of lymph-node post-capillary venules to infection with Toxoplasma gondii have been studied in mice. The endothelial cells of the post-capillary venules were significantly higher in the female than in the male controls. Oophorectomy had no significant effect while orchidectomy increased the height of the cells. However, hexoestrol administration resulted in a rise of the height to maximum levels in the female and in the male gonadectomised animals. The endothelial cells of male and female control and gonadectomised mice were higher after infection with Toxoplasma while in the infected hexoestrol-treated animals, lower cells were seen. The number of lymphocytes passing through the post-capillary venule wall was increased by gonadectomy and decreased by hexoestrol administration in both sexes. The same pattern was seen in the infected groups. The influence of sex hormones on the post-capillary venules and its possible contribution to the differences seen in the immune response between the two sexes is discussed.