BCG-induced changes in the post capillary venules of the guinea pig lymph node

The post capillary venules (PCV) of the regional lymph nodes of BCG-injected male and female guinea pigs were examined under light and electron microscopy. The endothelial cells showed increased height and pyroninophilia. Their cytoplasm contained increased numbers of ribosomes and polyribosomes and prominent rough endoplasmic reticulum with occasionally dilated cisternae. The number of lymphocytes migrating through the PCV wall was also increased. The activation of the endothelial cells of PCV induced by BCG may increase the recirculation of lymphocytes from the blood stream. These may be of importance in the antitumour activity of BCG. In control guinea pigs the height of the endothelial cells of PCV was significantly greater in the female than in the male. After BCG injection this sex difference was still apparent.