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J Cell Biol. 1991 Jun;113(5):1069-80. Motility of bile canaliculi in the living animal: implications for bile flow. Watanabe N1, Tsukada N, Smith CR, Phillips MJ. Author information Abstract Modern fluorescence microscopic techniques were used to image the bile canalicular system in the intact rat liver, in vivo. By combining the use of sodium fluorescein secretion into bile, with digitally enhanced fluorescence microscopy and time-lapse video, it was possible to capture and record the canalicular motility events that accompany the secretion of bile in life. Active bile canalicular contractions were found predominantly in zone 1 (periportal) hepatocytes of the liver. The contractile movements were repetitive, forceful, and appeared unidirectional moving bile in a direction towards the portal bile ducts. Contractions were not seen in the network of canaliculi on the surface of the liver. Cytochalasin B administration resulted in reduced canalicular motility, progressive dilation of zone 1 canaliculi, and impairment of bile flow. Canalicular dilations invariably involved the branch points of the canalicular network. The findings add substantively to previous in vitro studies using couplets, and suggest that canalicular contractions contribute physiologically to bile flow in the liver.

Figure & Scanning electron micrographs of a fractured surface of rat livers. (a) Control liver. Note the chicken wire-like anastomosing network of bile canaliculi (arrowheads). Canalicular lumina are uniformly filled with microvilli. (S), sinusoid. (b) CB-infused liver. Note the marked tubular dilatation of bile canaliculi (arrowheads). (c) CB-infused liver. Bile canaliculi are extensively dilated. Note the saccular dilatation of bile canaliculi (arrowheads). (d) High magnification of the tubular dilatation of bile canaliculi in CB-infused livers. Note the complete loss of canalicular mlcrovilli and the greatly dilated canalicular lumen (arrowhead). (e) High magnification of the saccular dilatation of bile canalicnli in CB-infused livers. Mainly at the bifurcation of the canalicular system, bile canaliculi are saccularly dilated with loss of microvilli (arrowhead).