THE PATHOGENESIS OF POST-PARTUM NECROSIS OF THE ANTERIOR LOBE OF THE PITUITARY GLAND

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Abstract
From a histological study of the lesions which develop in the vessels of the human pituitary gland during the first 2 days after the onset of post-partum necrosis of the anterior lobe, it is concluded that the primary vascular disturbance is a spasm involving the arteries which supply the anterior lobe and the stalk. This arrests the portal blood supply and also the direct arterial blood supply to the lobe, but permits a slight circulation to continue in the stalk. If the spasm is relieved within about an hour the parenchyma suffers only a transient functional damage. If it continues for several hours all the tissues in the anterior lobe are killed and, when blood finally attempts to flow into the dead vessels, stasis and thrombosis occurs. This thrombosis is a secondary phenomenon and is not the cause of the necrosis. Variations in the extent and the duration of the spasm account for the variations in the size of the necrosis; in about half the cases the lesion involves 97 to 99% of the anterior lobe, but the pars tuberalis and a small amount of the pars interloralis always survive. The arterial spasm is certainly related to a severe general circulatory collapse at the time of delivery, but the reason for its very specific localisation to the anterior lobe of the pituitary gland remains obscure.