During fetal development, the liver is the site of blood formation (hematopoiesis). Blood cell formation is largely limited to red blood cells with considerably fewer white blood cells.
Although the fetal liver is also organized into classic liver lobules, the structure is more difficult to recognize because of the large number of blood cells in the hepatic sinusoids and dilation of blood vessels.
Lobule - most easily recognized after first identifying a central vein.
Central Vein - large venule at the center of the lobule. Although swollen with red blood cells, central veins can be distinguished from portal triads because they occur as single vessels.
Hepatocytes - anastomosing plates, one cell thick, radiate outward from the central vein separated by sinusoidal capillaries and supported by reticular fibers.
Blood Cells - many small, condensed and/or pyknotic nuclei of red blood cells are seen in the sinusoids. White blood cells are not easily recognizable with H&E.
Portal Triads - at the corners of each lobule (contains hepatic arterioles, portal venule, bile ductules and lymphatic vessels).