Background
The liver is a very well organized organ, implicated in an array of different functions. It is structured
by the hepatic lobule with the portal tracts, the liver cords and the centrolobular vein. The acinus is
the functional unit of the liver parenchyma and is divided into three zones, each zone having its own
specific microenvironment and metabolic functions. The functional zonation of the liver has been
mostly studied in mouse models, and never analyzed by immunohistochemistry on human slides in
detail. Another important structure in the liver is the canal of Hering that serves as the junction
between the bile canaliculi formed by the hepatocytes and the bile ductules at the portal tract
border. Its demonstration on slides remains challenging.
Objectives
To visualize and measure the functional zonation in healthy livers, livers with vascular diseases and
cirrhotic livers.
To visualize and determine a reference number of canals of Hering, bile ductules and bile ducts per
portal tract profile in the healthy liver.
Materials and Methods
The surgical samples of 45 patients (10 healthy livers; 18 cirrhotic livers and 17 vascular disease
livers) were analyzed by two different original double immunohistochemical techniques. To study the
zonation, we targeted the glutamine synthetase protein to highlight zone 3 together with the
arginosuccinate synthetase to highlight zone 1. For the analysis of the canals of Hering, slides were
stained with anti-CD10 allowing to recognize the canalicular pole of the hepatocytes and anti-CK19
that identifies the cholangiocytes, therefore showing the junction between hepatocytes and
cholangiocytes defined as the location of the canals of Hering. After being stained, all sections were
scanned and processed by a microscope imaging software. An algorithm was designed to measure
zonation surfaces. Canals of Hering, ductules and ducts were counted manually.
Results
The healthy and vascular disease livers showed the expected pattern of zone 1 and zone 3 in the
periportal and perivenous areas, respectively. The findings show that zone 1 was larger than zone 3
in the healthy and vascular disease liver, with relative measurements becoming more variable in the
latter. In the cirrhotic liver, the analysis was less consistent and demonstrated the remodeling of the
liver architecture. Regarding the canals of Hering, only 33,71% of portal tracts present a visible canal
of Hering in healthy liver sections.
Conclusions
Double immunohistochemistry is an elegant technique to study the functional structure of the liver.
This pilot study paved the way for further analyses in healthy and diseased livers.