TRANSLATIONAL AND CLINICAL MEDICINE - Georgian Medical Journal

Introduction: While mechanisms of liver regeneration after partial hepatectomy are extensively studied, the specific structural transformations following resection and re-resection are less explored. Study aims to compare architectural differences between normal liver tissue and tissue after primary and repeated partial hepatectomy, exploring the long-term effects on the vascular bed and overall liver structure.

Methods: We analyzed liver tissue from 24 Wistar albino male rats, using histology, histochemistry, immunohistochemistry, and scanning electron microscopy of vascular corrosion casts. Comparative study was conducted through morphometric analysis, comparing the data of control and study (liver resection and re-resection) groups.

Results: 

• After 9 months of partial hepatectomy, liver undergoes significant changes, featuring remodeled lobules of varying sizes. The presence of "mega-lobules" is observed, housing hypertrophic hepatocytes with diverse shapes, primarily in the first and third zones of the acinus. These altered lobules exhibit an increased abundance of connective tissue. Additionally, sinusoidal capillaries exhibit multiplication through the both mechanisms - "sprouting" and "splitting", confirmed by appearance of  the typical blind-ended ramifications and “septs” on the vascular corrosion casts;
• After 6 months of repeated partial hepatectomy following a 9-month regeneration, hepatocyte hypertrophy is more pronounced in the 3^rd zone of liver acinus. The sinusoidal network is also remodeled, in particular, the diameters of the casts are increased, as well as the number and sizes of the "protrusions" and "vills" developed on them. The local dilations resulted from the merging of 3-4 sinusoids (sinusoidal lakes) were observed. Quite often the areas containing such patterns are difficult to distinguish from small tributaries of the hepatic veins (central and sublobular veins) on histological slices. In comparison with the changes developed in 9 months after PH, the number and size of mega-lobules as well as the content of connective tissue fibers are increased.

Conclusion: Liver regeneration following 2/3 resection and re-resection is a complex, months-long dynamic process involving the spatial transformation, altering the shape and number of cellular, vascular, and connective tissue components, resulting in complete lobular structural remodeling.