Embolism And Thrombosis not infrequently occur and cause greater or less disturbances according to their location and magnitude. As a rule, no serious conditions arise, as the collateral circulation is so extensive. The hepatic artery is capable of supplying sufficient blood for both the nutrition and function of the organ, so that marked interference with the portal circulation does not necessarily result in infarctions.

If the portal vein is completely obstructed, the secretion of bile stops, the blood is retained in the portal system, and death may result. If the hepatic artery is obstructed the liver rapidly becomes necrotic.

Numerous small foci of necrosis may result from infectious emboli in the portal capillaries. Is known as focal necrosis and is seen in puerperal fever, and in septic conditions involving the portal system, also in various infectious diseases. These foci differ in color from red to yellow according to whether blood or fat is present in the greater amount. The interlobular portal vessels are frequently the seat of a hyaline thrombosis.

Infarctions of the liver, either hemorrhagic or anemic, are almost unknown, as the anastomoses of the hepatic vessels are so extensive.

Hemorrhage of the liver occurs in severe infections and intoxications.

Infiltration And Degeneration

Pigmentation of the liver may be hematogenous. The blood coloring-matter may not be completely transformed into bile-pigment and is deposited in the interlobular tissues, in the peripheral zones, and in the central area of the lobule. This occurs to some degree in nearly all diseases of the liver. Is marked in chronic congestion, amyloid disease, cirrhosis, and pernicious anemia. The pigment is found as dark brown granules, is probably hemosiderin, as it gives the iron reaction, a blue color when pure sulphuric acid and potassium ferrocyanid are added.

Biliary pigment due to the retention of bile is not uncommon. The liver becomes dark yellowish-green, at times almost black in color. Is most marked in the central zone of the liver lobules.

Pigment in the form of melanin resulting from blood destruction in chronic malaria, and also as anthracotic particles, is found occasionally.

Fatty infiltration is to a certain extent normal, is more marked the younger the individual. After a meal, particularly if rich in fat, there is an infiltration in the peripheral zones. This is soon removed if the hepatic functions are being carried on normally. If the oxidation does not take place properly the fatty infiltration may become of an extremely high grade. Is best seen in chronic tuberculosis, particularly if forced feeding has been indulged in, in maras-matic individuals and in alcoholics, especially when malt liquors have been consumed to excess.

The liver becomes much enlarged, is at times nearly twice its normal size; the edges are rounded, its color is a uniform yellow, and it is doughy, slight pressure causing an indentation. On section the knife will be covered with small droplets of fat. The center of the acini may be darker than the periphery on account of congestion. The cells, microscopically, are seen to contain comparatively large droplets of fats which show a marked tendency to coalesce and form one large drop which may greatly distend the cell and push aside its nucleus, giving rise to the "signet-ring" appearance. The infiltration begins in the periphery and extends inward. On account of the distention of the cells the blood-vessels may be hidden from view and so obstructed as to give rise to considerable anemia and diminishment of functional activity.

The cells in this condition do not appear to be much damaged and are apparently able to resume their work when the fat disappears.