A morphometric study on growth of bile canaliculi after partial hepatectomy

Haemodynamic and ultrastructural observations on the rat liver after two-thirds partial hepatectomy

Rat liver ultrastructure was investigated after partial hepatectomy (PH), by scanning and transmission electron microscopy. Portal pressure was monitored before and after PH and, after killing performed at 6, 12, 24, 48 h and 10 d, regenerating livers were fixed by portal vein perfusion under haemodynamic conditions identical to those existing in vivo. An early and persistent increase in portal pressure after PH was found (P < 0.01 for normal vs sham-operated controls). Ultrastructural study showed sinusoid dilatation and disappearance of the sieve-plate arrangement of small endothelial pores, thus leaving the parenchymal liver cell surface directly exposed to portal blood. Widening of sinusoids, endothelial fenestrations, intercellular spaces and spaces of Disse, was accompanied by dilatation of bile canaliculi. At 10 d, liver ultrastructure had returned to normal. Our observations suggest that a rise in portal pressure, as a consequence of PH, may be related to the observed ultrastructural changes in the liver.

Biliary secretion in the rat after partial hepatectomy

The secretory efficiency of the liver increased in rats at 12 hr after partial hepatectomy. The secretory efficiency was seen to decrease at 24 hr after partial hepatectomy and increased again at 2-4 days following liver resection. These changes would correspond to the evolution of the hepatocyte proliferative process. The secretion of bile acids expressed per 100 g of body weight had returned to normal at 16 days after partial hepatectomy, although choleresis and the secretion of inorganic electrolytes remained lowered.

Ultrastructural changes in the bile canaliculi and the lateral surfaces of rat hepatocytes during restorative proliferation

Ultrastructural changes in the bile canaliculi and the lateral surfaces of rat hepatocytes during regeneration following a two-third partial hepatectomy were studied by transmission and scanning electron microscopy. A marked increase in microvilli, widening of the intercellular spaces, and invagination and indentation of cytoplasmic membranes were seen in the lateral surfaces of hepatocytes during the early period after the operation. The density of the microvilli on the lateral surfaces gradually decreased and intercellular spaces returned to normal within 24 h, whereas the bile canaliculi revealed dilatation and tortuosity with elongation of microvilli. Hepatocytes during mitosis became rounded and showed dispersed microvilli on the sinusoidal surface. The bile canaliculi of mitotic hepatocytes were continuous with those of adjacent hepatocytes. On the 2nd or 3rd day posthepatectomy, hepatic plates became more than one-cell thick and hepatocytes showed occasional acinar arrangements around the dilated bile canalicular lumina. These features gradually returned to normal by one week after the operation. This study revealed unique sequential changes in the bile canaliculi and the lateral surfaces of hepatocytes during regeneration after partial hepatectomy.